Donald Trump’s pick for Secretary of State has played down the alleged murder of Vladimir Putin’s political opponents saying “these things happen”.

On the second day of his confirmation hearing in front of the Senate Foreign Affairs Committee, Rex Tillerson was asked about his closes ties to Moscow.

The former ExxonMobil chief executive was awarded the Russian Order of Friendship in 2013.

Senator Marco Rubio asked if he was aware that “people who oppose Vladimir Putin wind up dead all over the world – poisoned, shot in the back of the head”.

He replied: “People who speak up for regimes which are oppressive are often at threat and these things happen to them. In terms of assigning specific responsibilities, I’d have to have more information.

Continuing his line of questioning, Mr Rubio, the former Republican presidential candidate and rival to Mr Trump, asked whether Mr Tillerson believed Mr Putin was a “war criminal”.

He replied that he wouldn’t use that word about the Russian leader.

Mr Rubio, who expressed “serious concerns” about Mr Tillerson’s appointment, asked if he believed Mr Putin “and his cronies are responsible for ordering the murder of countless dissidents, journalists and political opponents”.

Mr Tillerson replied that he did not have enough information to comment on that.

“I believe when advising the president it is important to have access to facts and to a large body of information," he said. "Now I’m sure that I’ve never seen what is in the classified realm.

“I look forward, if confirmed, to becoming fully informed but I’m not willing to make conclusions on what is publicly available or publicly reported.”

Mr Tillerson’s nomination as the country’s most senior diplomat has attracted significant criticism over his closed ties to Mr Putin.

His former company has billions of dollars of oil contracts with Russia that it can only fulfil if the US lifts the sanctions imposed on Moscow after the downing of the MH17 jet over the Donetsk region of Ukraine in 2014.

This has led to accusations of a conflict of interest.

However, Mr Tillerson insisted that he supported Barack Obama’s decision to impose the sanctions following CIA and FBI revelations that Moscow allegedly tried to tamper with the result of the presidential election by hacking into the emails of the Democratic National Committee.