The UK Border Agency has been "highly selective" in its use of drugs seizure figures, the chair of the UK Statistics Authority has said.
Sir Michael Scholar has written to the Home Office to seek reassurances that figures were not released to generate positive news coverage.
He said if this was the case it would be "highly corrosive and damaging".
The UKBA said it took its responsibilities under the Statistics Authority's code of practice seriously.
The row comes amid attacks on border policy.
Brodie Clark resigned as head of the UK border force last week amid a row with Home Secretary Theresa May over the relaxation of passport controls during a pilot scheme last summer.
'Irregular and inconsistent'
The UKBA released figures on 4 November, for publication last Monday, showing that border officials at UK ports and airports seized more cocaine and almost double the amount of heroin from April-September 2011 than in the whole of the previous year.
But three days later, the official Home Office Statistical Bulletin showed the amount of cocaine seized by local police and border officials in England and Wales had actually fallen by a quarter between April 2010/11, compared with 2009/10, and the amount of heroin seized had halved.
Sir Michael described the publication of the first figures as "irregular and inconsistent" with the UK Statistics Authority's code of practice and the Ministerial Code, and said it should not happen again.
In his letter to Home Office Minister Damian Green, Sir Michael outlined the discrepancy between the two sets of figures.
"The 4 November press release, which appears not to have been published on either the Home Office or the UK Border Agency websites, and seems to have been distributed only to a select group of journalists, makes no reference to the forthcoming Statistical Bulletin.
"It was, I understand, produced without any involvement by, and without the knowledge of, the department's statisticians; and it is highly selective in its choice of statistics, in order, it seems, to show the UK Border Agency in a good light."
The letter went on to say: "It has been suggested to me that one motivation for this release was to generate positive news coverage ahead of the release of the National Statistics which showed a decline in the volume of drug seizures.
"I would welcome your reassurance that this is not the case. Were it to be the case, the authority's view is that this would be highly corrosive and damaging to public confidence in official statistics."
Shadow home secretary Yvette Cooper called for "an urgent investigation by the Cabinet Secretary into whether there has been a breach of the Ministerial Code by either Damian Green or Theresa May".
"Sir Michael's letter is incredibly serious and brings into question the 'highly selective' use of statistics by ministers," she said.
UKBA chief executive Rob Whiteman had said in the news release: "Our work to secure the border all day, every day continues to show significant results despite the efforts of organised crime gangs to circumvent our controls."
And Mr Green had said that, "stopping harmful drugs like heroin and cocaine means we're helping keep communities safe and preventing criminals exploiting the UK".
A UK Border Agency (UKBA) spokesman said: "We regularly use management information to highlight our operational work, while continuing to take our responsibilities under the UK Statistics Authority's code of practice seriously.
"We will be replying in due course."
BBC 15 November 2011
Dear Drugs-Forum readers: We are a small non-profit that runs one of the most read drug information & addiction help websites in the world. We serve over 4 million readers per month, and have costs like all popular websites: servers, hosting, licenses and software. To protect our independence we do not run ads. We take no government funds. We run on donations which average $25. If everyone reading this would donate $5 then this fund raiser would be done in an hour. If Drugs-Forum is useful to you, take one minute to keep it online another year by donating whatever you can today. Donations are currently not sufficient to pay our bills and keep the site up. Your help is most welcome. Thank you.