Although Banerjee is yet to formally announce her decision, she made it known to Prime Minister Atal Behari Vajpayee yesterday. Home Minister Lal Krishna Advani and West Bengal BJP unit president Tapan Sikdar too attended the meeting.

Banerjee is learnt to have agreed to the BJP's proposal for a common manifesto and joint campaign by the alliance partners in West Bengal. A seat-sharing formula was also evolved at the meeting, as per which the BJP will leave 29 of the 42 Lok Sabha seats in the State to the Trinamool Congress.

The BJP had contested 14 seats and the Trinamool Congress 29 in the 1998 Lok Sabha elections, with both parties fielding their candidates for the Midnapore seat, eventually won by former Home Minister Indrajit Gupta of the Communist Party ofIndia (CPI). In a bid to give a tough fight to Gupta, the BJP had decided not to contest the seat and allow only the Trinamool Congress to field its candidate from Midnapore. Though Sikdar was adamant on the BJP contesting from Midnapore, the matter was resolved after the Prime Minister's intervention.

The BJP has swapped another seat with the Trinamool Congress: Raiganj, held by West Bengal Congress working president Priya Ranjan Das Munshi, with Balurghat.

The BJP will contest from Balurghat, leaving the relatively tougher Raiganj to the Trinamool Congress, sources close to Banerjee said.

Banerjee wanted to field former Congress member of Parliament Golam Yazdani, who has won the Raigunj seat three times in the past against Dasmunshi.

Besides Banerjee, the Manipur Congress led by Nipamacha Singh, which was closely working with the Trinamool Congress, is also learnt to have decided to join the NDA.

The Manipur Congress was part of the Progressive Alliance comprising former Congress leaders, formedby Mamata Banerjee in association with Suresh Kalmadi and the Loktantrik Congress Party of Naresh Agrawal, about six months ago.

The sole Manipur Congress MP, Thoiba Singh, had voted in favour of the Vajpayee Government in the no-confidence motion tabled by the Prime Minister in April.

Meanwhile, the BJP got a fillip in Arunachal Pradesh today, with the political advisor to former chief minister Gegong Apang, a former minister and 36 others joining it after resigning from the Arunachal Congress.

Nani Rebia, Apang's political advisor, and former minister Gyati Taka, said they joined the BJP to strengthen the hand of Atal Bihari Vajpayee who, they considered, is the fittest to be Prime minister.