Tánaiste Frances Fitzgerald has raised questions about Donald Trump's fitness to be US president.

The Fine Gael minister was speaking following the release of a 2005 recording in which the Republican candidate could be heard making lewd comments about women.

In the conversation with TV host Billy Bush, Mr Trump bragged about being able to kiss women and “grab them by the pussy" because of his fame.

The presidential hopeful initially said he was sorry "if anyone was offended" over what he called "locker room banter".

He went on to issue a more forthright video apology in the face of fierce backlash, saying anyone who knows him "knows these words don't reflect who I am".

Minister Fitzgerald, who attended the Democratic Party Convention in Philadelphia in July, described the comments as "deeply disturbing".

"I think it’s horrific what is being said in relation to women and celebrity being some some of excuse for sexual assault," she told reporters this afternoon.

"I think they’re horrendous comments. I think it’s very disturbing what has been said about the portrayal of women and attitude to women.

"If locker room banter is to become an excuse for sexual assault, it's deeply disturbing, and I would consider it a major issue in terms of the candidacy of anybody for the American presidency."

She added: "There’s another country making a decision about their president. At the end of the day, it’s for the voters in that country.

"But I certainly think the kind of views expressed by him raise serious questions about his fitness or eligibility to be president of the United States."