Any attempt by Iran to close the Strait of Hormuz would be illegal and would not succeed, Defence Secretary Philip Hammond said on Thursday, adding that British naval forces would continue to play a part in maintaining security in the Gulf.

Disruption to the flow of oil through the Straits of Hormuz would threaten regional and global economic growth, Hammond said in a speech to the Atlantic Council, a U.S. thinktank, during a visit to Washington.

Any attempt by Iran to close the Straits would be illegal and would be unsuccessful, he said, according to a text of his remarks released in London.

Hammond said the Royal Navy would continue to play a substantial role as part of the Combined Maritime Forces, a U.S.-led, Bahrain-based naval force drawn from 25 nations whose missions include counter-piracy, counter-terrorism and security in the Gulf.

Britain has mine counter-measure vessels maintaining freedom of navigation in the Gulf, he said.

Iran threatened last week to stop the flow of oil through the Strait of Hormuz if foreign sanctions were imposed on its crude exports over its nuclear ambitions, a move that could trigger military conflict with economies dependent on Gulf oil.

(Reporting by Adrian Croft; Editing by Mohammed Abbas)