Two other boats were rescued in the area in the past two weeks

One passenger contacted a relative in Italy by mobile phone on Thursday, after the boat hit bad weather.

It was spotted that night off the Italian island of Lampedusa, in high winds and three-metre waves (10 feet).

"It's improbable anyone has survived," Maltese army Captain Andrew Mallia told BBC News Online.

"They would have had a certain amount of water into the boat faster than they could get it out," he said.

"As of 1400 local time (1200GMT) we are suspending the search efforts, but we will be broadcasting a safety message, asking ships to keep a look out," he added.

The nationalities of the missing people are not known.

An Italian helicopter first spotted the boast at 2100 local time (1900GMT) on Thursday, but had to leave the scene because of a lack of fuel.

A German naval helicopter returned an hour later, but found no trace of the boat.

Two other small vessels carrying foreign nationals have been rescued off the coast of Malta in the past two weeks, Captain Mallia said.