The body which oversees the US intelligence services has formally summoned the president’s son, Donald Trump Jr, to testify again over his alleged dealings with Russia ahead of the 2016 general election.

The Senate Intelligence Committee, which is still examining Russian election interference, issued the subpoena after the testimony Mr Trump Jr gave to the Senate Judiciary Committee in September 2017 was later contradicted in a testimony given by his father’s former attorney Michael Cohen.

It is the first known subpoena of a member of Donald Trump‘s immediate family, and indicates the Senate panel is continuing with its own Russia investigation even after the release of special counsel Robert Mueller’s report on the same subject.

It is unclear if Mr Trump Jr will comply with the subpoena from the committee, which is chaired by Republican Senator Richard Burr of North Carolina.

According to CNN the president’s son is considering invoking his rights under the US constitution’s fifth amendment, which do not compel him to attend unless he is indicted by a grand jury (such a move would indicate a strong legal case against him).

The Democrat challengers to Trump in 2020 Show all 25 1 /25 The Democrat challengers to Trump in 2020 The Democrat challengers to Trump in 2020 Bernie Sanders The Vermont senator has launched a second bid for president after losing out to Hilary Clinton in the 2016 Democratic primaries. He is running on a similar platform of democratic socialist reform Getty The Democrat challengers to Trump in 2020 Joe Biden The former vice president recently faced scrutiny for inappropriate touching of women, but was thought to deal with the criticism well and has since maintained a front runner status in national polling EPA The Democrat challengers to Trump in 2020 Elizabeth Warren The Massachusetts senator is a progressive Democrat, and a major supporter of regulating Wall Street Reuters The Democrat challengers to Trump in 2020 Amy Klobuchar Klobuchar is a Minnesota senator who earned praise for her contribution to the Brett Kavanaugh hearings Getty The Democrat challengers to Trump in 2020 Michael Bloomberg Michael Bloomberg, a late addition to the 2020 race, announced his candidacy after months of speculation in November. He has launched a massive ad-buying campaign and issued an apology for the controversial "stop and frisk" programme that adversely impacted minority communities in New York City when he was mayor Getty Images The Democrat challengers to Trump in 2020 Tulsi Gabbard The Hawaii congresswoman announced her candidacy in January, but has faced tough questions on her past comments on LGBT+ rights and her stance on Syrian President Bashar al-Assad Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Pete Buttigieg The centrist Indiana mayor and war veteran would be the first openly LGBT+ president in American history Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Deval Patrick The former Massachusetts governor launched a late 2020 candidacy and received very little reception. With just a few short months until the first voters flock to the polls, the former governor is running as a centrist and believes he can unite the party's various voting blocs AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Beto O'Rourke The former Texas congressman formally launched his bid for the presidency in March. He ran on a progressive platform, stating that the US is driven by "gross differences in opportunity and outcome" AP The Democrat challengers to Trump in 2020 DROPPED OUT: Kamala Harris The former California attorney general was introduced to the national stage during Jeff Sessions’ testimony. She has endorsed Medicare-for-all and proposed a major tax-credit for the middle class AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Bill De Blasio The New York mayor announced his bid on 16 May 2019. He emerged in 2013 as a leading voice in the left wing of his party but struggled to build a national profile and has suffered a number of political setbacks in his time as mayor AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Steve Bullock The Montana governor announced his bid on 14 May. He stated "We need to defeat Donald Trump in 2020 and defeat the corrupt system that lets campaign money drown out the people's voice, so we can finally make good on the promise of a fair shot for everyone." He also highlighted the fact that he won the governor's seat in a red [Republican] state Reuters The Democrat challengers to Trump in 2020 DROPPED OUT: Cory Booker The New Jersey Senator has focused on restoring kindness and civility in American politics throughout his campaign, though he has failed to secure the same level of support and fundraising as several other senators running for the White House in 2020 Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Wayne Messam Mayor of the city of Miramar in the Miami metropolitan area, Wayne Messam said he intended to run on a progressive platform against the "broken" federal government. He favours gun regulations and was a signatory to a letter from some 400 mayors condemning President Trump's withdrawal from the Paris Climate Accord Vice News The Democrat challengers to Trump in 2020 DROPPED OUT: Kirsten Gillibrand The New York Senator formally announced her presidential bid in January, saying that “healthcare should be a right, not a privilege” Getty The Democrat challengers to Trump in 2020 DROPPED OUT: John Delaney The Maryland congressman was the first to launch his bid for presidency, making the announcement in 2017 AP The Democrat challengers to Trump in 2020 DROPPED OUT: Andrew Yang The entrepreneur announced his presidential candidacy by pledging that he would introduce a universal basic income of $1,000 a month to every American over the age of 18 Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Julian Castro The former San Antonio mayor announced his candidacy in January and said that his running has a “special meaning” for the Latino community in the US Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Marianne Williamson The author and spiritual adviser has announced her intention to run for president. She had previously run for congress as an independent in 2014 but was unsuccessful Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Eric Swalwell One of the younger candidates, Swalwell has served on multiple committees in the House of Representatives. He intended to make gun control central to his campaign but dropped out after his team said it was clear there was no path to victory Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Seth Moulton A Massachusetts congressman, Moulton is a former US soldier who is best known for trying to stop Nancy Pelosi from becoming speaker of the house. He dropped out of the race after not polling well in key states Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Jay Inslee Inslee has been governor of Washington since 2013. His bid was centred around climate change AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: John Hickenlooper The former governor of Colorado aimed to sell himself as an effective leader who was open to compromise, but failed to make a splash on the national stage Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Tim Ryan Ohio representative Tim Ryan ran on a campaign that hinged on his working class roots, though his messaging did not appear to resonate with voters Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Tom Steyer Democratic presidential hopeful billionaire and philanthropist Tom Steyer is a longtime Democratic donor AFP/Getty

Another option may be for him to simply not appear at all, the broadcaster said, citing “one source”.

A person “close to the president’s eldest son”, who requested anonymity to discuss the matter, told AP Mr Trump Jr has continued to cooperate by producing documents and answering written questions.

The Senate Intelligence Committee has interviewed many of the same witnesses who spoke to Mr Mueller’s team, and the committee has recently begun re-interviewing witnesses.

These include the president’s son-in-law, Jared Kushner, who made a second appearance earlier this year.

The committee’s renewed interest in talking to Mr Trump Jr comes after Cohen testified earlier this year and said he had briefed Mr Trump Jr approximately 10 times about a plan to build a Trump Tower in Moscow before the presidential election.

But Mr Trump Jr had told the Senate Judiciary Committee in 2017 he was only “peripherally aware” of the plans.

The panel has also investigated a meeting between Mr Trump Jr, other Trump campaign staff and a Russian lawyer.

Emails leading up to the meeting promised “dirt” on Hillary Clinton.

Cohen became the first of the president’s inner circle to allege that, in 2016, Mr Trump knew in advance his eldest son was meeting Russians who claimed to have compromising information on Ms Clinton.

Mr Mueller’s report, released last month, said Cohen recalled being in Mr Trump’s office “when Mr Trump Jr told his father that a meeting to obtain adverse information about Clinton was going forward".

But the report said Mr Trump Jr told the Senate Judiciary Committee, however, that he did not inform his father about the emails or the upcoming meeting.

This week Cohen arrived at prison to start a three-year sentence for crimes including tax evasion and campaign finance violations related to hush-money payments made to protect his former boss.

A spokeswoman for the Senate Intelligence Committee would not confirm the subpoena. But Maine Senator Susan Collins, a Republican member of the panel, hinted after Cohen spoke behind closed doors to the Senate intelligence panel that the committee would want to talk to Mr Trump Jr again.

She said senators “clearly need to re-interview some witnesses whose accounts [Cohen] contradicts".