FCA director of supervision Clive Adamson spent over £4,000 on a two-day supervisory visit to New York, figures published by the regulator show.
The FCA has published details of the expenses claimed by Adamson, chief executive Martin Wheatley, chairman John Griffith-Jones and other senior staff between October and December.
They show Adamson claimed £3,902 for foreign travel and £282 for foreign accommodation and subsistence during the period, which covers flights to New York and a one-night stay.
Adamson was visiting regulated firms which are headquartered in New York and meeting with US regulators.
A spokesman for the FCA says that under its travel policy, staff can travel business class for flights which are over five hours long. The policy also states that flights should be booked 42 days in advance where possible.
The New York flight was business class but was booked less than 42 days in advance.
Also during the three-month period, Adamson spent £980 on entertaining, working lunches and hospitality.
Griffith-Jones spent £15,151 on foreign travel and £1,313 on foreign accommodation and subsistence over the period.
This covered a five-night trip to Washington, a four-night trip to China as part of a UK delegation including Chancellor George Osborne, a one-day visit to Basel and a two-day visit to Moscow.
In addition, Griffith-Jones spent £922 on domestic travel, which covered regional visits to Bristol, Manchester and Cardiff.
Wheatley spent £441 on foreign travel, which covered a Eurostar journey to Paris. He also spent £221 on domestic travel and £165 on domestic accommodation and subsistence. This covered flights to Edinburgh and a one-night stay.
A spokesman for the FCA says: “We of course seek to minimise the necessity of overseas travel. The FCA could not however fulfill its role as a financial regulator without regular meetings with other overseas regulators and visits to group head offices of the firms which it is responsible for in the UK.
“Much of the financial rules which govern the UK are determined in committees which meet outside the UK. The attendance of FCA personnel at such meetings is essential if the FCA is to discharge its role effectively and influence the international regulatory agenda on behalf of the UK Government and firms.”
In November, expenses details published by the FCA revealed Wheatley claimed over £1,800 in hotel and subsistence costs for four nights.