The US on Thursday said it has neither sought nor received assurances that the Pakistani army will not stage a coup, even as it made it clear that it supports a 'civilian-led government' in the country.

Acknowledging that chairman of the Joint Chiefs of Staff Gen Martin E. Dempsey has talked on phone to Pakistani Army chief Gen Ashfaq Parvez Kayani, a Pentagon spokesman said: "I'm not aware that we've sought any assurances, and I don't think we're aware that we've been given any."

"This is a matter for Pakistani officials and the government leaders there, military and civilian, to work out," Pentagon spokesman Navy Capt John Kirby said in first comments by US officials on the ongoing tussle between the army and government in Pakistan.

Echoing the sentiments that the developments were the internal matters of Pakistan, State Department spokeswoman Victoria Nuland said the US supports a 'civilian-led government' as it maintains 'strong relations' with the Pakistan military.

"We want to see all parties in Pakistan behave in a manner consistent with the country's constitution with the democratic process and civil discourse," she said after a meeting between Pakistan's new ambassador Sherry Rehman and Secretary of State Hillary Clinton at the State Department.

Nuland called the meeting a 'chance talk' to 'getting our relation back on the track in all its elements in the new year'.

Asked about Pakistan's political instability, she said US diplomats in Islamabad were monitoring the situation but insisted that these were internal matters.

The Pentagon acknowledged that there is a near-open conflict between civilian and military leadership in Pakistan but the spokesman declined to provide details of the conversation between the two military chiefs, merely saying it was their first contact since December 21.

The spokesman said Dempsey had a unusually close connection with Kayani, saying he had known his Pakistani counterpart since 1988 when both had attended the US army's Command and General Staff College at Fort Leavenworth in Kansas.

"My understanding is that Chairman Dempsey has been in contact with Gen Kayani. It was a productive and professional conversation. I'm not going to get into the details. But that call has taken place," Pentagon Press Secretary George Little told reporters.

The timing of the call was not divulged, except that it has taken place within recent days. The crisis-prone politics in Pakistan blew up after powerful army warned Prime Minister Yousuf Raza Gilani of 'grievous consequences' for his recent criticism of the military and ISI, and the Premier taking them head on by sacking the defence secretary over the memo scandal.

Meanwhile, The New York Times said that in what could add to the growing confrontation, army officials have warned that the army will 'not cooperate' with the new Defence Secretary who was appointed by Prime Minister Gilani after he sacked Lt Gen (retd) Naeem Khalid Lodhi.

"The army will not react violently, but it will not cooperate with the new secretary defence," a military officer was quoted as saying in the report.

The report said military officials have warned that the army would be likely to refuse to work with the newly appointed defence secretary Nargis Sethi, "signaling the possibility of a serious rupture between the army and the civilian government".

Pakistani analysts said in the report that the firing of Lodhi could be a potentially ominous sign that the festering conflict between the army and the civilian government had reached a critical stage.

Another military official, speaking on the condition of anonymity, said that relations between Lodhi and Gilani soured after the prime minister's staff put pressure on Lodhi to contradict statements about the controversial memo by army chief Gen Kayani and ISI boss Lt Gen Ahmad Shuja Pasha.

The two had told the Supreme Court last month that the memo, allegedly drafted by former ambassador to the United States Husain Haqqani, was authentic.

"The government had prepared a draft that stated that the Ministry of Defence does not agree with General Kayani and Genera Pasha's opinions about the veracity of the memo," said the military official, who was present during the discussions. "General Lodhi refused to sign the document, saying those were not his words."