Ministers have been urged to increase pressure on President Pervez Musharraf to hold free elections in Pakistan after declaring a state of emergency.
Lib Dem Chris Huhne said it was a 'mistake' not to pressure Pakistan
Liberal Democrat leadership contender Chris Huhne said it was a "mistake" for ministers not to pressurise Pakistan.
And Labour MP Mohammad Sarwar said Pakistan is "heading for disaster" and urged the international community to take a tougher stance.
The Foreign Office will "consider the implications" of the current situation.
A spokesman said it would look at the implications of Gen Musharraf's actions on "development and other programmes in Pakistan" amid reports that the US was reviewing its own financial assistance to the country.
Foreign Secretary David Miliband has said he was gravely concerned about the development, adding that the UK would raise concerns "at the highest levels".
He said it was "vital" for Gen Musharraf to hold "free and fair elections".
The foreign secretary also called for UK-based Pakistanis to use family connections to call for democratic rule.
The announcement of emergency rule came ahead of a Supreme Court ruling on the legality of the president's re-election victory in October.
In Pakistan, troops have been deployed inside state-run TV and radio stations and independent channels went off air.
Gen Musharraf declared the state of emergency amid rising Islamic militant violence ahead of the judges' decision.
Mr Huhne said the government risked leaving Britain isolated by failing to put enough pressure on Gen Musharraf.
"When the regime does change - as it is bound to do in the case of Gen Musharraf because this is the last throw of the dice for him - we are likely to find ourselves very isolated," he told ITV's Sunday Edition.
He said it is a "big mistake" not to put more pressure on Gen Musharraf "because frankly Pakistan is going to have a new democratic regime, there is going to be a change back and we are aligning ourselves with the wrong side".
And Mr Sarwar, a Pakistan-born Labour MP, told the BBC that the "situation is grave".
He said: "The Commonwealth, the European Union, the United States and Britain should make it clear to Gen Musharraf that our support is now conditional."
He said the international community should put pressure on Pakistan's president "to conduct fair and impartial elections as soon as possible", plus lift the state of emergency and "let the people decide who they think is the best person to run the country".
Former Pakistan prime minister Benazir Bhutto, who returned to the country from exile earlier this month, said she was consulting other opposition parties about what their next move should be.
Speaking on BBC1's Andrew Marr Show, she said: "My party and I cannot accept martial law, even in this so-called emergency.
"We are calling for the restoration of our constitution, we believe it is important that Gen Musharraf heeds his commitment to the supreme court and the people of Pakistan and steps aside as army chief."
Meanwhile, Hamant Verma, the editor of Eastern Eye - Britain's leading Asian newspaper - said few would have much hope in Ms Bhutto's return.
"She was blamed for the state of the country when she was in charge and now of course they are looking to her as the saviour but her track record shows she is even less able to run Pakistan than Gen Musharraf," he said.
"The British government don't have much leverage. What can they really do?"