The Dutch rejection of the European constitution raises profound questions about the future of the European Union, Foreign Secretary Jack Straw has said.
The future of the European Union is in jeopardy
Mr Straw is next week expected to shelve plans for a UK vote on the treaty, which France also rejected.
Tory leader Michael Howard said the constitution should be "dead and buried" but UK voters should have a say if other nations' referendums go ahead.
The Liberal Democrats argue there is now no prospect of a referendum.
Provisional final results of Wednesday's referendum in the Netherlands indicate that 61.6% of voters said "No" to the constitution and 38.4% approved it.
Mr Straw will make a full statement to the House of Commons on Monday on the impact of the referendums.
He is expected to say the Bill to allow a referendum in the UK will be put on hold indefinitely.
The BBC's political editor Andrew Marr said the government regards the constitution as "a take it or leave it treaty, which effectively has been left".
On Wednesday evening Mr Straw said: "The verdict of these referendums now raises profound questions for all of us about the future direction of Europe.
"In an era of globalisation, when nations need to find new ways to work together to tackle new problems, Europe needs to be capable of giving citizens the prosperity, security, and social justice they require in ways which fit the modern world," he insisted.
Speaking on Thursday, Conservative leader Mr Howard said it was too early to say whether the constitution was dead but he hoped it was.
He argued the rejection of the constitution should be seen as a "tremendous opportunity" to rethink the shape of the EU and return powers from Brussels to the UK.
"The EU is too centralised, too remote, too unaccountable and it does too much," he said.
Mr Howard added: "If other countries are to have referendums then the British people should have a referendum too."
Liberal Democrats foreign affairs spokesman Sir Menzies Campbell said there was no point in a referendum on a treaty which was "not going to fly".
He said "zealots" were being unrealistic in calling for a referendum so they could claim a "No" vote was a sign of the UK voting against Europe.
"It will become clear that the government's responsibility is to pull together something out of what is essentially a mess," he said.
Lord Kinnock, a former vice-president of the European Commission, said the public had not been properly informed about the European Union by their governments.
Speaking of a "triumph of ignorance", he said: "The reality is that people do not love what they do not know."
But UK Independence Party leader Roger Knapman criticised those who suggested the 'Yes' voters knew what they were doing and that "us poor little peasants who vote 'No', we're a bit muddled up".
Britain in Europe, the cross-party pro-Europe group, admitted the rejection of the constitution in the Netherlands made a UK referendum "extremely unlikely".
But campaign director Lucy Powell said the issues set out in the treaty "have not gone away" and reform was needed to make a Europe of 25 members work effectively.
The No campaign's Matthew McGregor welcomed the result.
He said: "Pro-euro campaigners have tried to dismiss the result of the French referendum by saying that it wasn't really a vote against the constitution."
"That wasn't true for France and its even more unbelievable this time."