Crews of commercial vessels thwarted five piracy attempts in the Gulf of Aden by taking evasive measures and using fire hoses to repel attackers, even when shots were fired, US-led navies said.

"The pro-active measures taken yesterday (Tuesday) by merchant vessels are exactly what we have been recommending," said Vice Admiral Bill Gortney, commander of Combined Maritime Forces, a 20-nation navy coalition in the Gulf and off parts of Africa's coast where Somali pirates have been active.

"The Coalition has been working with the commercial shipping industry and the International Maritime Organization to recommend ... self-protection measures. These measures range from proactive lookouts and evasive maneuvering to embarking professional security teams," he said in a statement.

Somali pirates have been causing havoc in one of the world's busiest shipping areas connecting Europe to Asia and the Middle East, taking large ransoms, hiking insurance costs, and threatening humanitarian supplies. - Reuters