"There has been a fall in the level of frequency and intensity of the tremors," the national emergency operations centre said in a statement, adding that authorities remain on "red alert" to deal with any threat posed.

The tremors, first felt after an eruption in the volcano's main crater late Friday, caused no casualties or damage, although some residents fled their homes in the shadow of the mountain after the earth shook on Saturday night.

Colonel Mogne Daho, head of the emergency centre, told AFP that a team of scientists from the nearby island of Reunion was expected in the capital Moroni this week in the wake of the volcanic activity.

There have been a number of scares in recent years after activity in the 2,361-meter (7,746-foot) Mount Karthala, the only active volcano in the three-island chain.

In May 2006, the mountain spat up smoke and jets of molten into its crater, creating eerily glowing red clouds in the night skies over the capital Moroni just 15 kilometers (nine miles) away.

In November 2005, it spewed huge plumes of ash that blanketed the isle and the capital, temporarily depriving the city's 250,000 inhabitants of potable water.

In April 2005, nearly 10,000 villagers at the base of the mountain fled their homes after similar emissions of ash started widespread fears of drinking-water contamination.

Mount Karthala last had an overflow magma eruption in 1977, when lava destroyed the village of Singani, some 20 kilometres (12 miles) south of Moroni, and toxic gas was released into the air but did not cause any deaths.

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