Sanaa: Iran has dispatched a destroyer and another naval ship to waters off Yemen, raising the stakes as a Saudi-led air campaign against rebels there continues.

The Iranian manoeuvre comes as the US deepens its support for the Saudi-led coalition, boosting weapons supplies and intelligence-sharing and carrying out the first US aerial refuelling mission of coalition fighter jets.

In this picture taken on April 7 and released by the semi-official Fars News Agency, the Iranian warship Alborz leaves Iran bound for waters off Yemen. Credit:AP

The Iranian warships were sent to the strategic Bab al-Mandab strait as part of an anti-piracy campaign to "safeguard naval routes for vessels in the region", Iranian Rear Admiral Habibollah Sayyari was quoted as saying by state broadcaster Press TV.

Securing navigation in the narrow strait was a key reason for the Saudi-led air and maritime blockade that began after Yemen's internationally recognised president, Abed Rabbu Mansour Hadi, fled the country two weeks ago as the rebels closed in on Aden, Yemen's second-largest city, where he was based.