London: British Prime Minister Gordon Brown yesterday evening defended his refusal to hold a referendum on the European Union's controversial new treaty, ahead of a crunch vote in parliament.

His government was not expected to lose the vote in the lower House of Commons, but the prime minister was keen to minimise a rebellion from his own side as they clashed with opposition lawmakers.

"If this was a constitutional treaty, we would hold a referendum. But the constitutional concept was abandoned," Brown told the leader of the main opposition Conservative Party, David Cameron.

Critics of the Lisbon Treaty, signed by the 27-nation bloc's leaders in December, have charged that it is broadly similar to the EU Constitution, which was left dead in the water when Dutch and French voters rejected it in 2005.

The referendum call is backed by large sections of Britain's notoriously eurosceptic press, which have maintained pressure on Brown ever since he succeeded Blair last June.

The Tories claim the government has given up centuries-old powers and freedoms to Brussels.