http://news.bbc.co.uk/1/hi/uk_politics/8597530.stm
Prime Minister Gordon Brown has acknowledged that he "misused" immigration figures, after being criticised by the statistics watchdog.
In a podcast on Friday, Mr Brown said net migration into the UK fell from 237,000 in 2007 to 163,000 in 2008 and provisionally 147,000 in 2009.
But the head of UK Statistics Authority agreed with a Tory complaint that he had made inaccurate comparisons.
Downing Street said it accepted the statistics had been "unclear".
But it insisted that Mr Brown had since corrected them.
The rebuke came hours after the prime minister talked up government progress on immigration.
In a speech in London, Mr Brown said there had been a significant drop in asylum claims and net immigration thanks to Labour's "tough and hard-headed" policy and warned would-be illegal migrants they were not "welcome" in the UK.
'Care needed'
In the podcast, Mr Brown cited the figures to argue that a new points system introduced in 2008 - determining which skilled workers from outside the EU can enter the country - had "radically changed the way we are dealing with immigration".
The Conservatives said the PM had used two different sets of statistics to make his case and left out important caveats about the figures.
They said he had failed to point out that the net immigration figure for 2009 only covered the year up to June, while asylum seekers and people overstaying their original visas were included in the figures for 2007 and 2008 but excluded for 2009.
Sir Michael Scholar, the head of independent UK Statistics Authority, said he had written to Mr Brown to point out that the figures he cited for net immigration between 2007 and 2009 were "not comparable".
In addition, he said the prime minister's comments had not taken into account the fact that the figure for 2007 had been revised.
However, Sir Michael noted that the figures used by Mr Brown in Wednesday's speech were correct.
He added: "The Statistics Authority hopes that in the political debate over the coming weeks all parties will be careful in their use of statistics, to protect the integrity of official statistics."
Responsibility
In response to Sir Michael's letter, a Downing Street spokesman said: "We accept that some of the statistics used in the prime minister's podcast were not strictly comparable and as a result were unclear.
"The figures he used in his speech are consistent with the analysis set out in the accompanying note from Sir Michael Scholar."
Immigration Minister Phil Woolas urged people not to "dance on a pin head" when it came to the battle over statistics.
"The fact is the figures are down," he told Channel 4 News. "That is what is important."
But shadow home secretary Chris Grayling said the prime minister had given an "inaccurate picture of his record on immigration".
"Britain should expect better from its prime minister," he said. "No wonder we need change."
BBC home affairs editor Mark Easton said that despite the watchdog's desire not to get involved in political controversy, it had found itself in the middle of a pre-election spat.
The Statistics Authority was set up by Mr Brown last year to ensure the correct use of official data.
It has ticked off both Labour and the Conservatives in recent months about their use of statistics, saying they had a responsibility to ensure their claims were not misleading."
Lies, damn lies and statistics
Prime Minister Gordon Brown has acknowledged that he "misused" immigration figures, after being criticised by the statistics watchdog.
In a podcast on Friday, Mr Brown said net migration into the UK fell from 237,000 in 2007 to 163,000 in 2008 and provisionally 147,000 in 2009.
But the head of UK Statistics Authority agreed with a Tory complaint that he had made inaccurate comparisons.
Downing Street said it accepted the statistics had been "unclear".
But it insisted that Mr Brown had since corrected them.
The rebuke came hours after the prime minister talked up government progress on immigration.
In a speech in London, Mr Brown said there had been a significant drop in asylum claims and net immigration thanks to Labour's "tough and hard-headed" policy and warned would-be illegal migrants they were not "welcome" in the UK.
'Care needed'
In the podcast, Mr Brown cited the figures to argue that a new points system introduced in 2008 - determining which skilled workers from outside the EU can enter the country - had "radically changed the way we are dealing with immigration".
The Conservatives said the PM had used two different sets of statistics to make his case and left out important caveats about the figures.
They said he had failed to point out that the net immigration figure for 2009 only covered the year up to June, while asylum seekers and people overstaying their original visas were included in the figures for 2007 and 2008 but excluded for 2009.
Sir Michael Scholar, the head of independent UK Statistics Authority, said he had written to Mr Brown to point out that the figures he cited for net immigration between 2007 and 2009 were "not comparable".
In addition, he said the prime minister's comments had not taken into account the fact that the figure for 2007 had been revised.
However, Sir Michael noted that the figures used by Mr Brown in Wednesday's speech were correct.
He added: "The Statistics Authority hopes that in the political debate over the coming weeks all parties will be careful in their use of statistics, to protect the integrity of official statistics."
Responsibility
In response to Sir Michael's letter, a Downing Street spokesman said: "We accept that some of the statistics used in the prime minister's podcast were not strictly comparable and as a result were unclear.
"The figures he used in his speech are consistent with the analysis set out in the accompanying note from Sir Michael Scholar."
Immigration Minister Phil Woolas urged people not to "dance on a pin head" when it came to the battle over statistics.
"The fact is the figures are down," he told Channel 4 News. "That is what is important."
But shadow home secretary Chris Grayling said the prime minister had given an "inaccurate picture of his record on immigration".
"Britain should expect better from its prime minister," he said. "No wonder we need change."
BBC home affairs editor Mark Easton said that despite the watchdog's desire not to get involved in political controversy, it had found itself in the middle of a pre-election spat.
The Statistics Authority was set up by Mr Brown last year to ensure the correct use of official data.
It has ticked off both Labour and the Conservatives in recent months about their use of statistics, saying they had a responsibility to ensure their claims were not misleading."
Lies, damn lies and statistics