Talks to resolve Zimbabwe's deep crisis have stalled after opposition leader Morgan Tsvangirai refused to sign a framework for negotiations, his party said on Thursday.

Both Tsvangirai's Movement for Democratic Change and the ruling ZANU-PF party of President Robert Mugabe are under strong African and world pressure to negotiate after the widely condemned re-election of Mugabe last month.

While the talks foundered, diplomats in Brussels said European Union members would agree on Tuesday to widen sanctions on Zimbabwe, including more travel bans and asset freezes on Mugabe's inner circle and measures against companies with links to him.

The MDC and ZANU-PF began preliminary talks under South African mediation last week. MDC spokesman Nqobizita Mlilo said Tsvangirai had refused to sign an initial memorandum of understanding. "We won't have people putting it on our heads that we have to sign an agreement when our demands have not been met," he said.

The MDC has set several conditions for talks, including the end of government-backed violence it says has killed 113 of its supporters and the acceptance of Tsvangirai's victory in the first round of the presidential vote on March 29. Tsvangirai, who fell short of an absolute majority, pulled out of the run-off citing violence against his party.

Mlilo said the MDC now awaited the result of a meeting between South African President Thabo Mbeki and the African Union's top permanent official, Jean Ping, on Friday. "We want to see the outcome of the meeting between Mr Ping and President Mbeki tomorrow and then we will take it from there," Mlilo said.

Mbeki was appointed by regional grouping SADC last year to mediate in the Zimbabwe crisis, which has ruined a once prosperous economy and flooded neighbouring nations with millions of refugees.

Critics say Mbeki's discreet diplomatic approach favours Mugabe and has been ineffective. The MDC wants an AU envoy appointed. The tougher EU sanctions will for the first time include freezing the assets and banning the activities of companies with links to Mugabe's leadership, an EU diplomat said.