The coalition government in Maharashtra on Tuesday faced a crisis with Deputy Chief Minister Ajit Pawar of NCP resigning in the wake of allegations of a massive irrigation scam as 20 more of his party ministers offered to quit in a bid to mount pressure on Congress.

The simmering tensions in the 13-year-old coalition came to the fore with the resignation of Ajit, 53-year-old nephew of NCP chief Sharad Pawar, following reports of scam to the tune of thousands of crores of rupees in irrigation projects during his tenure as Water Resources minister between 1999 and 2009.

NCP suspects the hand of Congress behind these reports targeting Ajit and other NCP leaders.

However, Sharad Pawar dismissed reports of crisis or pressure building on him to get the party out of the coalition, saying there is no question of "destabilising" the state government or any more resignations.

His party leader Majid Memon said the resignation of other ministers was done as a measure of solidarity with Ajit.

Ajit put in his papers today after discussions with his uncle in the wake of allegations of irregularities in clearing irrigation projects worth thousands of crores of rupees.

"I have sent my resignation to the Chief Minister's office....I am ready to face a CBI probe," Ajit told a hurriedly called press conference, adding he will stand vindicated.

His resignation comes on top of strains in the coalition that has been struck by the worst internal crisis after Chavan took over as Chief Minister less than 2 years ago.

Chavan said he would discuss with both NCP and Congress leaders before deciding on Ajit's resignation.

 On a day of hectic developments, 20 other NCP ministers have sent their resignations to state party chief Madhukar Pichad with a demand that the party should quit the coalition.

The NCP legislature party will meet on Wednesday to chalk out its future strategy.

Union Minister and NCP Vice President Praful Patel spoke of a "big conspiracy" to defame the NCP not only by opposition parties but also by "our friends".

He dismissed as baseless reports that the resignation would pave the way Sharad Pawar's daughter Supriya Sule replacing Ajit as Deputy Chief Minister.

Ajit, who held Finance and Energy portfolios, said he will continue to be the leader of NCP legislature party as long as he enjoyed the support of the legislators. He would not accept any post till his name is "cleared", he said.