Kushner, who is a senior adviser to US President Donald Trump in addition to being married to his eldest daughter, Ivanka, will be questioned by both House and Senate committees looking into whether Trump's Republican campaign received Russia's aid in winning last year's elections.

Questions at the closed-door interrogations are likely to revolve around his meetings with Russia's ambassador to Washington, the head of a major Russian bank and a Russian lawyer. The latter took place in the presence of Trump's son, Donald Jr., who has also been invited to testify at a hearing before the Senate Judiciary Committee on Wednesday, although his participation was still unclear as of Monday.

Kushner is to testify before the Senate Intelligence Committee on Monday and the House of Representatives Intelligence Committee on Tuesday, his lawyer said.

He will also have to respond to charges that he tried to set up a secret back channel to Moscow.

'No improper contacts'

In a statement released hours before his appearance in front of the Senate committee, Kushner said he had four contacts with Russian officials, which he described as normal in his former role as a liaison between the Trump campaign and foreign governments.

But he denied working together with the governments of any other country to help his father-in-law win the presidency.

"I did not collude, nor know of anyone else in the campaign who colluded, with any foreign government," he wrote, adding that he had had no "improper contacts." 

Read more: What you need to know about the five inquiries looking into Donald Trump, James Comey                        and Russia

Mysterious meeting

Members of both committees have said they are particularly interested to hear details of the June 2016 meeting involving Russian lawyer Natalia Veselnitskaya, Kushner, Trump Jr. and former Trump campaign manager Paul Manafort.

"There's a lot we want to know," Adam Schiff, the leading Democrat on the House committee, told broadcaster CBS's "Face the Nation" program.

"We certainly want to know about several of the meetings that have been taking place," he added.

He also said that the intelligence panel could ask Kushner to return and testify further if any questions remained open after Tuesday.

The House and the Senate are carrying out their own investigations into the allegations of possible collusion, in addition to a separate probe led by special counsel and former FBI director Robert Mueller.

Read more:  Trump Jr. meeting relevant to Russia probe: US special counsel Mueller

Enmeshed with Moscow?

Ever since coming to power in January, the Trump administration has had to contend with allegations that the president's campaign aides worked with Russia, which US intelligence agencies have accused of meddling in the election that took the former real-estate mogul to the White House.

Both Moscow and Trump have denied the charges.

However, Trump Jr. released emails earlier this month that at least showed him seeming to relish the idea of being given damaging information about Trump's Democratic rival, Hillary Clinton, by the Russian government.

His father has called the investigations by Congress and the Justice Department politically motivated.

"As the phony Russian Witch Hunt continues, two groups are laughing at this excuse for a lost elections taking hold, Democrats and Russians," the president wrote in his favorite medium, Twitter, on Sunday.

tj/ (Reuters, AFP)