JOHANNESBURG, South Africa — European Union foreign ministers agreed Tuesday to toughen sanctions against Zimbabwe's President Robert Mugabe to pressure him to share power with the opposition ahead of the opening of talks between Zimbabwe's rival parties in South Africa.

Mugabe and opposition leader Morgan Tsvangirai agreed Monday to formal talks about sharing power to end Zimbabwe's crisis, deepened by three months of state-sponsored electoral violence. The talks were expected to begin later Tuesday at a secret location, said Mukoni Ratshitanga, spokesman for South African President Thabo Mbeki who is mediating.

The agreement includes a key opposition demand for an end to the political violence that has killed dozens, injured thousands and sent tens of thousands fleeing from their homes. Mbeki persuaded the parties to agree to complete negotiations within two weeks, in a sudden show of urgency which may have been heightened by intense international pressure.

In Brussels, French Foreign Minister Bernard Kouchner said EU foreign minister agreed to expand their sanctions blacklist of people linked to Mugabe's government to 172 people, adding 37 individuals and four companies believed to financially support Mugabe and his ZANU-PF party. The list already contains 131 people, including Mugabe and members of his Cabinet, under measures passed in 2002.

"We want there to be sanctions because sanctions have an effect," Kouchner told reporters.

The foreign ministers said in a statement they decided to expand sanctions "against those responsible for the campaign of violence that marked the elections," and vowed to take additional "appropriate measures" if Mugabe fails to hand over power to the opposition.

The revised list is subject to a travel ban and assets freeze and its expansion was meant to keep the pressure on Mugabe to cooperate with Tsvangirai in the power-sharing talks.

The EU ministers also agreed to tighten a travel ban on Mugabe. Under new rules all member nations will have to approve a visit to an EU country before he would be allowed to enter the 27-nation bloc. Currently, only a majority needs to approve his visits.

In the past year, Mugabe has twice attended international events in Europe, circumventing an EU ban.

They also agreed to study further measures, notably on dissuading European companies from doing business with Mugabe's government because of concerns he and his ministers are using businesses to move around their cash.

The 37 added names include military chiefs and a journalist from a pro-Mugabe newspaper. The companies added are those the EU believes are being used to back Mugabe's ZANU-PF party, including a farm cooperative and ZANU-PF's publishing arm.

The bloc also has in place a ban on arms sales.

The EU ministers also concluded that Mugabe's June re-election in a presidential run-off vote was illegitimate and they welcomed negotiations between Mugabe and Tsvangirai.

British Foreign Secretary David Miliband said a face-to-face meeting between Mugabe and Tsvangirai on Monday was only "a first step," and EU nations were expecting more proof that Mugabe was willing to sign up to a transitional government with the opposition.

"It requires an end to the violence, it requires an end to the ban on humanitarian NGO's getting around Zimbabwe. Those are the first steps toward a resolution of the Zimbabwean crisis," Miliband told reporters.

Monday's agreement gives broad outlines for discussion and no indication what Mugabe, who has clung to power for 28 years, may be willing to concede in talks with the opposition.

The leaders agreed on the need to work together "in an inclusive government" — the closest language to a power-sharing accord. And they committed to creating a "genuine, viable, permanent and sustainable solution."

Tsvangirai, in an open message to Zimbabweans, said Tuesday that the agreement "offers the most tangible opportunity in the past 10 years to improve the lives of our fellow citizens." However, he cautioned "our signatures alone do not guarantee that we will be able to make the most of this opportunity."

Mugabe said they must "chart a new way" — but act without influence from Europe or the United States. In the past, he has branded Tsvangirai a Western puppet.

Mugabe is expected to send Justice Minister Patrick Chinamasa and the minister for social welfare, Nicholas Goche.

The chief negotiator for Tsvangirai's party is secretary-general Tendai Biti and he will be assisted by deputy secretary-general Elton Mungoma. A third, breakaway faction of Tsvangirai's party will be represented by its secretary-general and deputy, Welshman Ncube and Priscilla Misihairabwe-Mushonga

The opposition won a concession to broaden the mediation of Mbeki, whom they accuse of being partial to Mugabe. Mbeki agreed Friday to include representatives of the United Nations and the African Union.

Mbeki has long argued that dialogue — and not punitive sanctions — is the only way to deal with the longtime African leader.

Michelle Faul reported from Johannesburg and Constant Brand reported from Brussels.