MAPUTO: Southern African leaders held an emergency summit Thursday aimed at hauling Zimbabwe's fragile power-sharing deal out of a three-week impasse that has paralysed the unity government.

Mozambican President Armando Guebuza opened the closed-door summit with a call on Zimbabwe's rival leaders to overcome their differences to ensure political and economic stability.

"We want to see the parties reiterate their commitment to continue working together to overcome the present challenges, always putting, as they have done, the national interest of their country first," Guebuza said in opening remarks distributed to reporters.

"Everything possible should be done to maintain political stability and the continued influx of foreign investment necessary for the progress of the ongoing process of relaunching the country's economy."

A coalition of Zimbabwean civil society groups meanwhile said the unity deadlock between President Robert Mugabe and Prime Minister Morgan Tsvangirai had been accompanied by "a marked increase in threats to the rule of law".

The Zimbabwean Civil Society Monitoring Mechanism held a press conference on the sidelines of the summit to denounce an increase in abductions, torture, farm invasions and political violence in recent weeks.

The group urged leaders from the Southern African Development Community (SADC), the regional bloc that organized the summit, to take a tougher stance on Zimbabwe.

"Our presence is meant to put pressure on SADC to ensure that they cease treating Mugabe with kid gloves," spokesman McDonald Lewanika told AFP.

"SADC countries (need) to begin to take the Zimbabwean question seriously and to do what is good, not just by Mugabe but by the people of Zimbabwe."

Long-time rivals Mugabe and Tsvangirai agreed to form a unity government in February in the wake of deadly violence that erupted after disputed elections last year.

The pact helped arrest Zimbabwe's economic free-fall and created an opening to repair its international ties, amid Western calls for greater signs of reform from Mugabe, the country's ruler since 1980.

But the agreement has been plagued by disputes over the appointment of provincial governors and Mugabe's unilateral re-appointment of central bank chief Gideon Gono and attorney general Johannes Tomana.

Tsvangirai's Movement for Democratic Change (MDC) also claims its lawmakers have been targeted for government persecution.

Tsvangirai's decision to suspend ties on October 16 was sparked by the renewed detention of MDC treasurer Roy Bennett on terrorism charges.

Armed police also raided an MDC house last month claiming they were searching for weapons. But the MDC accused Mugabe's ZANU-PF party and security forces opposed to the unity government of staging the raid for political reasons.

After cutting ties with the "dishonest and unreliable" Mugabe camp, Tsvangirai embarked on a regional tour, appealing to southern African leaders to intervene in the stand-off.

Thursday's summit was organised by regional bloc SADC's security and defence troika, which currently comprises Mozambique, Swaziland and Zambia and is chaired by Guebuza.

Leaders from the troika countries, current SADC chair the Democratic Republic of Congo and regional powerbroker South Africa will hear a report from a fact-finding mission that visited Zimbabwe last week, a top official said.

Tomaz Salomao, secretary general of the Southern African Development Community, said the summit would also address the political situations in Lesotho and Madagascar, both of which have been plagued by instability in recent months.