He was arrested on Wednesday night to investigate the basis of his prediction, police spokesman Ranjith Gunasekera said.

The astrologer predicted that a planetary change on 8 October will be inauspicious for parliament and the government may not be able to contain rising living costs - a forecast which correspondents say has already been made by private economists.

So convinced are Sri Lankan politicians over the accuracy of astrology that many have their own personal seers who decide the auspicious times to launch any new initiative.

President Rajapaksa has declared himself to be a believer, telling foreign reporters earlier this year that he has often consulted a favoured astrologer for advice on what time to make speeches or to depart for trips.