The G8 leaders today called for tougher UN sanctions against Zimbabwe, increasing international pressure on the African pariah state.

Russia and Italy have fallen into line with demands to extend existing sanctions, after initially opposing tougher action against Zimbabwe whose veteran leader President Robert Mugabe has just been re-elected after a campaign marred by state-sponsored violence, intimidation and rape.

"We will take further steps, inter alia introducing financial and other measures against those individuals responsible for violence" in Zimbabwe, the G8 said in a statement.

The strongly worded communiqué states that the G8 does not accept the legitimacy of any Zimbabwean government that does not reflect the will of the people. It says that the G8 leaders are deeply concerned at the humanitarian crisis in Zimbabwe, and urges Mr Mugabe's government to work with the opposition to resolve the crisis peacefully.

The statement also calls on the UN to send an envoy to broker a deal. Gordon Brown said that he was pleased that all eight G8 countries had signed up to such a powerful message. "This is the strongest statement. It shows the unanimity of the international community reflecting the outrage people feel," he said.

The G8 deal, with the crucial inclusion of Russia, will enable Britain, France, Germany and the United States to move at the UN Security Council later this week, pressing it to adopt the draft resolution imposing tough trade measures on Zimbabwe.

It will leave China comparatively isolated in its opposition to sanctions in the UN Security Council.

The move came as Zimbabwe’s state media reported that Mr Mugabe’s Zanu-PF party was to resume talks with the opposition Movement for Democratic Change under the mediation of South African President Thabo Mbeki. So far the negotiations have appeared to produce no progress.

Mr Mugabe was beaten into second place in the presidential ballot and the MDC won a swingeing majority in Zimbabwe's parliament in elections in March. So far however parliament has not met as MPs have not been sworn in.

Meanwhile, Zanu-PF loyalists led by the army have carried out a relentless programme of beatings, rape and killings aimed at opposition voters. As a result, the MDC leader Morgan Tsvangirai pulled out of the second round of the presidential ballot last month, allowing Mr Mugabe to claim that he had been re-elected unopposed.

At present Mr Mugabe is prevented from most foreign travel outside Africa by personal sanctions that target him and other members of his regime.

In imposing fresh strictures, the G8 leaders were said to be concerned that they were not seen to be hurting ordinary Zimbabweans, who have already suffered from poverty, food shortages, mass unemployment and hyperinflation that has rendered their currency worthless.

News of the deal was first leaked by Silvio Berlusconi, the Italian Prime Minister, in unofficial remarks as the summit progressed.

"The need and the urgency was indicated for sanctions at the UN Security Council," said Mr Berlusconi, in asides to reporters at the conference. He said that he had a change of heart when it seemed that "even Russia decided to go ahead, it seemed to me important to join in, voting unanimously."

Previously Italy and Russia had argued for a negotiated settlement whereby Mr Mugabe would relinquish power but stay on as a titular head of state over a government of national unity.