Nicola Sturgeon has insisted her US tour is focused on trade after opponents criticised her for promoting Scottish independence on the trip.

The First Minister told an audience at California's Stanford University on Tuesday that she "fervently" wanted the country to become independent and was "fairly certain" there would be a second referendum.

It prompted criticism from the SNP's opponents, with Conservative chief whip John Lamont saying it was a "great shame" Ms Sturgeon was using the taxpayer-funded trip to promote independence.

Scottish Labour business manager James Kelly added: "Even on a foreign trip Nicola Sturgeon can't stop campaigning for another divisive independence referendum.

"When Nicola Sturgeon is abroad she should be representing the interests of all the people of Scotland, not trying to build up support for a second referendum that the majority here don't want."

After her speech at Stanford, Ms Sturgeon said: "The focus of the trip hasn't really been on independence. The focus of the trip has been on trade and business and investment relationships.

"There is, I detect, a real desire to strengthen economic links between the United States and Scotland. That's been the focus of the trip.

"Obviously there is heightened awareness and interest in the Brexit discussion and also what that means for Scotland's constitutional future."

Ms Sturgeon confirmed she has no plans to meet any members of Donald Trump's administration during her US visit but insisted it was not a "deliberate decision" to avoid the president.

"This trip has been principally business-focused so we're not going to Washington on this occasion," she said.

"I fully expect, during his presidency, President Trump will come to the UK and come to Scotland. As First Minister of Scotland, I'm not going to decline to meet him."

Ms Sturgeon said she expected the UK Government to respond "fairly soon" to her Section 30 letter formally requesting a second referendum on Scottish independence and she would outline her response after Easter.

Ms Sturgeon will give a speech at the United Nations headquarters in New York on Wednesday before completing her five-day US trip on Friday.