DUBAI, (Reuters) – Pirates have hijacked two foreign ships off Somalia within 24 hours in a new spate of attacks in the lawless waters, foreign navies patrolling the region said on Thursday.

The seizure of the ships undermined hopes that the arrival of a flotilla of ships from Western and Asian countries was starting to rein in piracy near one of the world’s busiest shipping lanes.

The European Union’s Maritime Security Centre said a 9,000 tonne Greek-owned Panamanian registered vessel, with 19 crew, was attacked east of Somalia on Wednesday while a 23,000 tonne Norwegian owned and Bahamian registered vessel was captured on Thursday.

A U.S. Navy spokesman identified the second vessel as the Bow Asir.

“The cargo is unknown. There are 23 crew members aboard,” said Lieutenant Nathan Christensen, spokesman for the U.S. Fifth Fleet in Bahrain.

NATO said the other ship was the Nipayia.