The crisis over the Indo-US nuclear deal deepening in the wake of US statement that the pact with India would be terminated in the event of a nuclear test by New Delhi, the UPA government on Thursday continued with its Track-II diplomacy by exploring channels of negotiation with other top CPI-M leaders, ahead of the crucial politburo meeting this weekend.

Though External Affairs Minister Pranab Mukherjee sought to calm the frayed nerves declaring in the Lok Sabha that national interests would be protected by the deal, his assertion failed to cut ice with the Left leadership.

The CPI bluntly told the government that it cannot take the support of the Left parties for granted. “Don’t take the support of the Left parties for granted. The Left is a serious political force and reflects the concerns of the people. The government should understand this,” CPI leader D Raja told reporters after the Rajya Sabha adjourned for the day over the issue.

“Despite this, if the government goes ahead with the deal, then we will decide what we can do,” he said.

An emergency meeting of the party’s central secretariat has been convened on Friday to decide the future course of action. The politburo is scheduled to meet on August 17-18 in New Delhi to discuss the issue.

Since Prime Minister Manmohan Singh’s statement in Parliament that the deal would protect India’s interests, and his breakfast meeting with CPI-M general secretary Prakash Karat failed to convince the Left, it is learnt that Mukherjee has been asked by Congress party chief Sonia Gandhi and Dr Singh to hold further talks with the Left leaders to break the impasse.

Mukherjee also met CPI-M leader Sitaram Yechury on Thursday before making a statement in Parliament defending the deal and asserting India’s right to conduct future tests. The Prime Minister is also likely to have an interaction with West Bengal chief minister Buddhadeb Bhattacharya, who will attend be attending Friday’s politburo meeting.