Pakistan’s military has publicly rebuked Prime Minister Yousuf Raza Gilani over an escalating row.
The army warned of “serious ramifications with potentially grievous consequences” after the PM criticised military leaders in a media interview.
Meanwhile, Mr Gilani has sacked his defence secretary, who is seen as having close ties to the military.
Tensions have been rising in recent months between Pakistan’s civilian government and military leaders.
The latest row is a serious source of instability in Pakistan, where the military has ruled for more than half the country’s history after seizing power in a series of coups.
On Monday Mr Gilani was quoted telling China’s People’s Daily Online that Pakistan’s army chief and head of intelligence acted unconstitutionally by making submissions to a Supreme Court inquiry which has been rocking the government.
On Wednesday, the military hit back with an unusually strongly-worded statement.
“There can be no allegation more serious than what the honourable prime minister has levelled,” the statement said.
It said the prime minister had accused the army chief and the head of Inter-Services Intelligence of violating the constitution.
“This has very serious ramifications with potentially grievous consequences for the country,” it added, without saying what these might be.
A senior official told AFP news agency that the defence secretary, retired general Naeem Khalid Lodhi, had been removed from his post for gross misconduct.
The sacking is likely to heighten frictions with military leaders.
Many observers believe Gen Lodhi lost his job after writing to the Supreme Court saying the government had administrative, but not operational, control of the army.
State media said he was removed “for creating misunderstanding between state institutions”.
Last month Mr Gilani said conspirators were plotting to bring down his government, without specifically blaming the military. That prompted army chief Gen Ashfaq Kayani to dismiss coup rumours.
Relations between the government and the military have seriously deteriorated in recent weeks.
The Supreme Court is investigating an anonymous memo which sought US help to avert a possible military coup in Pakistan following the killing by US forces of al-Qaeda leader Osama Bin Laden in May.
It is not clear who wrote the memo or conveyed it to the Americans. They say they received it but took no action.
Pakistan’s military – deeply humiliated by the discovery of Bin Laden on Pakistani soil and the secret US operation to kill him – has been incensed by the affair.
The scandal has already cost Pakistan’s former ambassador to Washington, Husain Haqqani, his job. He denies any role in the memo, as does President Asif Ali Zardari.
He could be forced to quit if the trail is found to lead to his door. The Supreme Court investigation aims to get to the bottom of the scandal.
Mr Zardari’s government is also on a collision course with the judiciary, which wants to reopen old corruption cases in which the president argues he is innocent.