Iran has sent six warships into international waters including the Gulf of Aden, a local newspaper reported on Tuesday, just days after it test-fired a new missile that can reach some parts of Europe.

"We have dispatched six warships to international waters and the Gulf of Aden," naval commander Habibollah Sayari was quoted as saying in the Jomhuri Eslami.

"This mission shows our increased capability in dealing with any foreign threat," he said.

The newspaper said the warships were dispatched to confront potential attacks on Iran's commercial vessels and oil tankers by pirates off the Somali coast.

Iran, the world's fourth largest oil producer, relies on tankers to deliver crude to customers through the Gulf and the Strait of Hormuz, the waterway through which about 40 percent of the world's oil supplies are shipped.

In the past, Iran has warned that it could block the Strait if attacked over its controversial nuclear drive.

Iranian officials said on May 14 that the Islamic republic had dispatched two warships to the Gulf of Aden but it was unclear whether they were among the six announced by Sayari.

His announcement comes on the heels of Iran test-firing a new surface-to-surface missile called Sejil-2 with a range of up to 2,000 kilometres (1,200 miles).

Iran has boasted in the past of developing new weapons systems only to be met with scepticism from Western defence analysts.

Its naval access stretches along the Gulf in the south, the Sea of Oman, and the Caspian Sea in the north.

In November, a Hong-Kong registered cargo ship chartered by Iran was hijacked in the Gulf of Aden by Somali pirates before being released in January.

In October, authorities in Tehran reportedly paid a ransom to secure the release of an Iranian merchant ship hijacked off the Somali coast two months before.