Adding to the central government's woes, ally DMK announced that it would join a nationwide strike Thursday against FDI in retail and the hike in diesel prices.

At her aggressive best, Banerjee told the media that Trinamool's six ministers -- one cabinet and five ministers of state -- would submit their resignations to Prime Minister Manmohan Singh in New Delhi Friday.

"We can't be a party to anti-people decisions. We had expected the government would roll back their decisions. But they have decided against it. 

"So we ... are withdrawing our support from UPA-2," she said, speaking mainly in Bengali.

"This government has lost its credibility," she added.

However, Banerjee gave a lifeline to UPA, saying she would reconsider withdrawal of support if the government took back its decision to allow foreign direct investment (FDI) in multi-brand retail, cut the hiked diesel prices by Rs.3, and raised the number of subsidised cooking gas cylinders each household can get in a year to 12. 

It was the most serious hiccup yet in the Trinamool's three-year-relatinship with the government that had seen Banerjee stepping down as the railway minister to form the government in West Bengal and forcing her successor Dinesh Trivedi to quit last year for hiking fares.

Simultaneously, the Congress said Tuesday night that it still viewed the Trinamool as a valuable ally.

"Till a final decision is taken, we consider the Trinamool a valuable ally," Congress general secretary Janardan Dwivedi said.

The Trinamool, with 19 members in the 545-seat Lok Sabha, was the second largest constituent in the multi-party UPA.

This would make the UPA more dependent on the Samajwadi Party and Bahujan Samaj Party, which extend outside legislative support to the UPA regime.

Within minutes, the Bharatiya Janata Party (BJP) asked the government to prove its majority in the Lok Sabha.

Marxist leader Sitaram Yechury suggested that Banerjee could still go back on her decision. "We should wait till Friday," added Rashtriya Janata Dal leader Lalu Prasad.

At her presser, Banerjee lashed out at the Congress, saying the FDI decision was unveiled to divert attention from the coal blocks allocation controversy involving the government.

She accused the Congress of acting unilaterally, without giving respect to its allies. "We cannot tolerate this."

"If FDI is allowed in retail market, where will the retailers go? There will be a disaster," she said. 

Banerjee said she spoke to UPA chairperson Sonia Gandhi four days back, requesting her to persuade the government to roll back the decisions on FDI, diesel and cooking gas cylinders. 

"But nothing of that sort happened." 

The Trinamool chief demanded to know why the government was not bringing back the huge volumes of black money allegedly stashed by Indians in foreign banks.

"Somebody has to bell the cat," she said, explaining her decision Friday. 

A day after the government announced its economic decisions, Banerjee had declared that her party would take "hard decisions" if these were not taken back. Her 72-hour deadline ended Monday.

The Trinamool-UPA break-up comes two days before a nationwide strike called Thursday by all opposition parties against the economic decisions.