Theresa May has said she will not be afraid to raise Donald Trump's controversial remarks if the situation arises during her visit to Washington this week.

The day after more than one million women marched worldwide to protest against Trump, the British PM said she would welcome the new US president to the UK.

Mrs May, who departs for Washington on Friday, said the biggest statement about the role of women would be her, as female prime minister, talking to him.

In an interview on BBC's Andrew Marr show on Sunday she also reacted to the American president's inauguration speech, saying it had a 'clear message' in line with his campaign.

She was not concerned by his speech, saying instead he was doing what any leader would do to defend the interests of his or her country.

Mrs May confirmed they will talk about the special relationship between the US and the UK, a possible trading relationship, NATO and 'world challenges' such as terrorism and the conflict in Syria.

"I think free trade is important around the world, I believe globalisation is important, I believe this does bring economic benefits to our countries, but we do need to make sure ... that those economic benefits, that economic prosperity, is spread across the whole of the UK," she told Marr.

When probed several times over whether or not she knew about the nuclear missile misfire before the Trident renewal vote, May did not give a clear answer.

"I have absolute faith in our Trident missiles," she commented.

Earlier in the programme, Shadow Chancellor John McDonnell said both sides of the Trident argument would have expected the misfire to be reported and that 'questions need to be asked'.