Image copyright Tom Williams/Getty Images Image caption Robert Mueller has been tight-lipped about his investigations into alleged Russian interference

US special counsel Robert Mueller has disputed a claim that President Trump told his long-time lawyer Michael Cohen to lie to Congress.

Mr Mueller's office said the report by Buzzfeed was "not accurate".

The website said that Cohen had told investigators that Donald Trump had instructed him to lie about plans to build a Trump Tower in Moscow.

Mr Trump later denied the report saying his ex-lawyer had lied to investigators to "reduce his jail time".

On Saturday the president thanked Mr Mueller's office, saying the statement was "very appropriate".

Responding to the special counsel's statement, Buzzfeed editor-in-chief Ben Smith tweeted that he stood by the story.

Skip Twitter post by @benyt In response to the statement tonight from the Special Counsel's spokesman: We stand by our reporting and the sources who informed it, and we urge the Special Counsel to make clear what he's disputing. — Ben Smith (@benyt) January 19, 2019 Report

Democratic politicians have said they will investigate the allegations.

Media playback is unsupported on your device Media caption Trump's attorney general nominee William Bar tells Congress ordering someone to lie is obstruction

What did Mueller's office say?

In a brief statement, it said: "Buzzfeed's description of specific statements to the Special Counsel's Office, and characterisation of documents and testimony obtained by this office, regarding Michael Cohen's Congressional testimony are not accurate."

The statement did not say which parts of the BuzzFeed report were inaccurate.

It is extremely rare for Mr Mueller's office to issue such a statement.

The special counsel is investigating alleged Russian interference in the US presidential election and whether Trump campaign figures were complicit - a claim repeatedly denied by Mr Trump.

What did the Buzzfeed report say?

Buzzfeed said its report was based on testimony from two unnamed law enforcement officials investigating the matter.

Cohen told Congress that talks over the Trump Tower plan had taken place between September 2015 and January 2016, when the project was scrapped.

Media playback is unsupported on your device Media caption What does it take to impeach a president?

But he now says that the talks lasted until June, when Mr Trump was a candidate for president.

Quoting the officials, Buzzfeed said Cohen told the special counsel that after the November 2016 elections, Mr Trump "personally instructed him to lie" - by claiming that negotiations ended months earlier than they actually did - "in order to obscure Trump's involvement".

Mr Mueller had already revealed that Cohen lied about the date the Moscow Trump Tower project ended.

The Buzzfeed report also said Mr Trump had allegedly encouraged Cohen to plan a trip to meet Russian President Vladimir Putin during the election campaign.

Cohen was sentenced to 36 months in jail in December after he pleaded guilty to lying to Congress over the Trump Tower plan. He also admitted campaign finance violations and tax evasion.

In court he said his "weakness was a blind loyalty to Donald Trump" - whose "dirty deeds" he had felt compelled to cover up.

What has Mr Trump said?

Responding to the allegations in the report, Mr Trump said that Cohen was "lying to reduce his jail time".

He then posted a tweet late on Friday questioning Buzzfeed's editorial judgment, referring to the website's decision to publish a dossier in 2017 that alleged collusion between his election team and Russia.

"Remember it was Buzzfeed that released the totally discredited "Dossier," paid for by Crooked Hillary Clinton and the Democrats," he wrote in a Twitter post.

Skip Twitter post by @realDonaldTrump Remember it was Buzzfeed that released the totally discredited “Dossier,” paid for by Crooked Hillary Clinton and the Democrats (as opposition research), on which the entire Russian probe is based! A very sad day for journalism, but a great day for our Country! — Donald J. Trump (@realDonaldTrump) January 19, 2019 Report

What is the latest with the Russia investigation?

Mr Mueller's investigation is still ongoing and it is unclear when he will submit his findings to the attorney general.

It is up to the attorney general to notify Congress and decide whether the report will be released publicly.

Mr Trump's nominee for attorney general, William Barr, who is currently undergoing confirmation in Congress, has said he will make as much of the Mueller report public as possible but has not promised to publish it all.

Image copyright Reuters Image caption Cohen was sentenced in New York last month

So far Mr Mueller's investigation has led to charges against more than two dozen Russians, as well as several people connected to Mr Trump himself, including his former national security adviser and the former chairman of his election campaign.

A number of them, including Cohen, are known to be co-operating with Mr Mueller's inquiry.

Cohen must report to prison by 6 March, but before that, he has agreed to testify before the House Oversight Committee in February.