WASHINGTON (AFP) - Mutual admiration between Donald Trump and President Vladimir Putin continued to flower Friday, when the Republican presidential frontrunner praised Russia's leader as forceful and popular.

"I think that he's a strong leader, he's a powerful leader," Trump told MSNBC television. "He's represented his country."

The real estate mogul was speaking a day after Putin lauded him as "talented" and "outstanding."

"When people call you brilliant, it's always good, especially when the person heads up Russia," the one-time reality TV star said on MSNBC's Morning Joe programme.

Trump brushed off the assertion by the show's co-host Joe Scarborough that Putin "kills journalists and political opponents and invades countries."

"He's running his country and at least he's a leader, unlike, you know, what we have in this country," he responded.

"I think our country does plenty of killing, also, Joe," Trump added. "There's a lot of stupidity going on in the world right now, Joe. A lot of killing going on."

Only when asked, for a third time, whether he condemned the killing of journalists and political opponents, did Trump change tack: "Oh sure, absolutely," he said.

The surprise leader of the Republican presidential race, Trump has only gained in popularity since making abrasive anti-Muslim comments in the wake of the California shooting this month.

Two recent polls show him at new heights with the support of 41 per cent of Republican voters.

Rivals in the primary race for 2016 have sought to use Putin's endorsement against the billionaire.

"To get praise from Vladimir Putin is not going to help Donald Trump," former Florida Governor Jeb Bush told CNN on Thursday.

Putin made the remarks when asked about the prospect of a new US president during his annual news conference in Moscow on Thursday.

"He is a very outstanding man, unquestionably talented," Putin told journalists.

"It's not up to us to judge his virtue, that is up to US voters, but he is the absolute leader of the presidential race."