New Delhi - India's parliament is to convene in a special session from July 21 as the ruling coalition aims to prove it continues to hold a majority after left-wing parties withdrew their support in protest of a civilian nuclear deal with the United States, news reports said Friday.

India's Cabinet Committee on Parliamentary Affairs made the decision at a meeting in New Delhi, the PTI news agency reported, quoting political sources.

The special session is to convene July 21 and a vote on a confidence motion on the coalition was expected the next day, the report said.

A spokesman for the prime minister's office said, however, that a final decision on the special session would be taken later Friday.

Prime Minister Manmohan Singh met President Pratibha Patil Thursday to inform her that the Congress Party-led United Progressive Alliance was seeking the vote and wanted it to occur as soon as possible.

A day earlier, four left-wing parties with 59 members in parliament broke their ties with the ruling coalition and demanded a confidence vote, saying the coalition was reduced to a minority government.

The communists, who described the nuclear deal as a "sell-out" of India's strategic sovereignty, decided to quit the coalition after Singh met US President George W Bush on the sidelines of the Group of Eight summit of major world economies in Japan and discussed progress on the deal.

The India-US nuclear agreement would allow the United States to trade fissile materials and technology with India, ending a three-decade ban. India would in return open its civilian reactors to international inspections. (dpa)