Image copyright AFP Image caption Republican Senator Orrin Hatch (right) was angry at Democrats' "obstruction"

Republicans on a US Senate committee have forced through approval of President Donald Trump's nominees for health and treasury secretaries, despite a Democratic boycott.

Republicans changed the rules in order to allow Mr Trump's picks to go ahead.

The next stage of the confirmation process is a full vote in the Senate.

Mr Trump said he would advise Senate Republicans to "go nuclear" if his Supreme Court pick was blocked.

The phrase is a reference to the so-called nuclear option, a parliamentary procedure which would change the rules and allow the Senate to approve a nomination with a simple majority.

Senate Democrats have implied they will try to filibuster or talk out a vote on Judge Neil Gorsuch, Mr Trump's nominee for the nation's highest court, which would mean the confirmation would require a supermajority of 60.

For cabinet positions, the president's nominees are first grilled by the relevant Senate committee, before passing to the full Senate for confirmation.

Image copyright Reuters Image caption Steve Mnuchin, chosen to be Mr Trump's treasury secretary, used to work for Goldman Sachs

The nomination of Jeff Sessions as attorney general was approved in a full justice committee vote along party lines on Wednesday.

But after Democrats on the finance committee said on Tuesday that they needed more time and information about Mr Trump's picks for health secretary, Tom Price, and treasury secretary, former banker Steve Mnuchin, Republicans on the finance committee got them through anyway.

The Republicans suspended a rule that requires at least one Democrat to be there for the vote in order that they could go through despite the opposition party's absence.

Finance committee chairman Senator Orrin Hatch was angry at the Democrats' boycott.

"We took some unprecedented actions today due to the unprecedented obstruction on the part of our colleagues," he told reporters.

Senator Sherrod Brown, one of the Democrats on the committee, tweeted his reasons for boycotting the committee hearing:

Image copyright Twitter/@SenSherrodBrown

Republicans hold a 52-48 majority in the full Senate and the membership of Senate committees reflects this ratio.

More on Donald Trump's nominations

Meanwhile, UN Secretary General Antonio Guterres has called for Mr Trump's ban on people from seven mainly Muslim countries entering the United States to be lifted "sooner rather than later".

The restrictions, which last for 90 days, were imposed last Friday by Mr Trump in an executive order. He said it was to safeguard the US from terrorism.

But Mr Guterres said the measures were not an effective way of protecting countries from terrorists.