US President Donald Trump said he feels “sad” about the conviction of his former campaign manager Paul Manafort.

But he hasn’t publicly reacted to former personal lawyer Michael Cohen’s guilty pleas to felonies, including campaign finance violations he stated he carried out in co-ordination with Trump.

Speaking to reporters in Virginia, Mr Trump said Manafort was a “good man”.

“Paul Manafort’s a good man. He was with Ronald Reagan, he was with a lot of different people over the years, and I feel very sad about that. It doesn’t involve me, but I still feel it’s a very sad thing that happened,” Mr Trump said.

The US President told reporters Manafort’s conviction “has nothing to do with Russian collusion.”

Manafort was convicted on Tuesday in Virginia on charges brought by special counsel Robert Mueller, who is investigating Russian interference in the 2016 election and potential obstruction of justice.

Cohen pleaded guilty in New York, and said he and Trump arranged the payment of hush money to porn star Stormy Daniels and a former Playboy model to influence the election.

A jury found Manafort guilty of eight counts with a judge declaring a mistrial on 10 other charges.

After deliberating for four days, the jury of six men and six women told the judge it had failed to reach a decision on 10 of the 18 criminal counts Manafort faces in the first trial stemming from Special Counsel Robert Mueller’s investigation of Russia’s role in the 2016 US election.

Manafort was charged with 18 counts of tax evasion, bank fraud and hiding foreign bank accounts in the first case brought to trial by Mr Mueller.

He pleaded not guilty to all the charges.

The government can retry Manafort on the 10 charges that the jury failed to reach a verdict on.

Mr Trump has repeatedly called the probe a “witch hunt” and has called on Mr Mueller to wrap up his investigation.

Prosecutors say Manafort collected $US65 million ($A88 million) in foreign bank accounts from 2010 to 2014 and spent more than $US15 million ($A20 million) on luxury purchases in the same period, including high-end clothing, real estate, landscaping and other big-ticket items.

Manafort faced up to 305 years in prison if convicted on all charges.