U.S. Senate Democrats and Republicans squabbled on Thursday over whether Secretary of State nominee Rex Tillerson's tax returns should be examined as part of the confirmation process.

Apart from routinely submitting financial disclosure forms and ethics documents, Tillerson, chief executive officer of Exxon Moile, should also submit his tax returns, Ben Cardin, top Democrat on the Senate Foreign Relations Committee said on Thursday in a letter to other Democrats on the committee.

"I think it is an important part of vetting this candidate because he has never made public disclosures of this type, as he has worked at Exxon Mobile for his entire career and has never been in public service," said Cardin.

"Mr. Tillerson was actively engaged with many foreign governments that could become relevant if confirmed as Secretary of State," he added.

The Senate Foreign Relations Committee cannot require nominees to provide tax returns and the committee's Republican Chairman Bob Corker immediately blasted Democrats for playing politics.

"As is long-standing precedent for nominees by the Senate Foreign Relations Committee, the committee has not asked Mr. Tillerson to provide copies of his tax returns," said Corker in a statement, adding that the confirmation procedures for Tillerson would be the same as carried out "since well before I joined the committee 10 years ago."

Tillerson, 64, is the Texas-based oil company's CEO since 2006. Like Trump, he has no government experience and so far little is known of Tillerson's views about foreign affairs.

However, as Exxon's CEO, Tillerson oversees business operations in over 50 countries and has known Russian President Vladimir Putin since 1990s when they first met.

Tillerson was awarded Russia's Order of Friendship in 2013, a state decoration to reward foreign nationals whose work is aimed at the betterment of relations with Russia.

So far, Tillerson's ties to Russia had raised bipartisan concerns in the U.S. Congress.

source: Xinhua