Most of the island's remaining residents live in the northern "safe zone" and no injuries were reported in Friday's eruption.

The news will come as a blow to thousands of refugees from Montserrat who were hoping to return to the island.

Molten rock and mud poured down for several hours and a huge cloud of ash rose over 10,000 metres (35,000 feet) high.

A BBC correspondent in the region says the eruption came as a surprise to scientists monitoring the volcano and is likely to force the postponement of plans to re-open the centre of the island.

Scientists have been monitoring the Soufriere volcano

Several thousand people fled Montserrat in 1997 because of repeated eruptions and lava flows which destroyed the capital, Plymouth, and made large areas of the former British colony too dangerous to live on.

The volcano, which had been inactive for nearly 400 years, forced around 8,000 people to flee to Britain or neighbouring Caribbean islands.

Scientists at the Montserrat Volcano Observatory said on Friday the volcano's dome, a mound of debris in its crater, was unstable and he warned residents to stay away from Soufriere, which is at the southern end of the 39 square-mile (62 sq km) island.

Montserrat's government information officer, Richard Aspin, said: "It just goes to show you that you never know when volcanoes go back to sleep. The volcano is still a live volcano and we can't forget that."