LONDON, June 25 (Reuters) - The United Nations’ shipping agency on Thursday paused an evacuation effort to get hundreds of stranded ships and thousands of seafarers out through the Strait of Hormuz after a vessel was attacked in the Gulf of Oman.

"I have been informed of an attack today in the Gulf of Oman on a vessel which passed through the Strait of Hormuz. This vessel did not transit under IMO’s evacuation framework," Arsenio Dominguez, Secretary-General of the U.N.'s International Maritime Organization (IMO), said in a statement.

"I have decided to temporarily pause its implementation in order to reconfirm that the necessary safety guarantees continue to be in place for the ships on our evacuation list and all those in the region."

The initiative, which was launched on Tuesday, was a voluntary option for ships and their crew to sail out of the Gulf using two routes – one via Iranian waters and the other via Omani waters, with U.S. oversight, the IMO said this week.

(Reporting by Jonathan Saul, Editing by William Maclean)