New Delhi, Sep 2 - Prime Minister Manmohan Singh and Congress chief Sonia Gandhi Wednesday expressed serious concern over the reported disappearance of a helicopter carrying Andhra Pradesh Chief Minister Y.S. Rajasekhara Reddy after it encountered inclement weather in the interior areas of the state.

'Sonia Gandhi and her office are continuously monitoring the situation,' Congress spokesperson Manish Tewari told reporters here, and added: 'We pray to God for his safety and hope that he returns to work soon.'

Both Prime Minister Manmohan Singh and Gandhi were in close touch with the Andhra chief minister's office and promised all help from the centre. The Congress party was also in constant contact with the state government and the state unit of the party, he said.

Four Indian Air Force (IAF) helicopters were despatched in the search mission.

Tewari refused to field further questions, stating there is a 'crisis situation in Andhra Pradesh'.

'It is an evolving situation; in view of the sensitivity of the matter, I will not say anything more,' he said.