document: The chairman of the House intelligence committee, Devin Nunes, told reporters that Paul Manafort had voluntarily offered to speak to the panel.
  Mr Nunes also contradicted Mr Trump's claim that Barack Obama had wiretapped him before the US elections.
  "There was no wiretapping at Trump Tower, that didn't happen," he said.
  However, Mr Nunes said he was concerned that the names of members of Mr Trump's transition team were "unmasked" during the surveillance of foreign individuals.
  Earlier this week, AP news agency reported that Mr Manafort had worked for a Russian billionaire to assist Russian President Vladimir Putin.
  Mr Manafort has insisted that he never worked for Russian interests.
  He had worked as Mr Trump's unpaid campaign chairman from March until August last year.
  He resigned after AP revealed that he had co-ordinated a secret Washington lobbying operation on behalf of Ukraine's ruling pro-Russian political party until 2014.
  The Trump administration has denied any collusion with Moscow, while Russia has always denied attempting to influence the US presidential election.
  Speaking to reporters on Friday, Mr Nunes said that he had invited FBI director James Comey and National Security Agency (NSA) chief Adm Mike Rogers to provide further testimony at a closed intelligence committee session.
  On Monday, Mr Comey told an open hearing that the FBI was investigating alleged Russian interference in the 2016 election, and said he saw no evidence that Mr Trump had been wiretapped by the Obama administration.
  Mr Nunes said there were questions that Mr Comey and Adm Rogers "could not answer in a public setting", so he was asking them to return for a closed session.
  However, Democrats have criticised Mr Nunes after he delayed a planned open hearing with ex Director of National Intelligence James Clapper, former CIA director John Brennan, and ex deputy Attorney General Sally Yates.
  The top Democrat on the committee, Adam Schiff, said that was an attempt to "choke off" information to the public.
summary: US President Donald Trump's ex-campaign chief has agreed to be interviewed by a panel investigating alleged links between the Trump team and Russia.