Washington: US Senator Elizabeth Warren has written to Secretary of State Michael Pompeo, seeking information on Vice-President Mike Pence's stay at a property belonging to US President Donald Trump during an official visit to Ireland.

US Vice-President Mike Pence, his wife Karen Pence and his mother Nancy Pence Fritsch arrive in Doonbeg, Ireland. Credit:AP

Warren said the incident was "another example of what appears to be open corruption in this administration." She asked about the costs associated with Pence's trip, whether the State Department reviewed his plans, and whether it was aware of a "suggestion" by the President for Pence to stay at the Trump International Golf Links & Hotel Doonbeg.

"This is only the latest instance in which government officials, companies or special interest groups have patronised the President's hotels – enriching the President and his family – in numerous cases, with taxpayer funds," Warren wrote in a letter dated September 4.

Trump on Wednesday said he never spoke to Pence about staying at the golf resort, contradicting a comment from the Vice-President's chief of staff. Pence stayed in Doonbeg on Monday and Tuesday, and met with Ireland's top officials in Dublin, about 200 kilometres away.