Zimbabwe's defeated presidential candidate Morgan Tsvangirai has prepared to mount a legal and political challenge against the "sham" election that may extend Robert Mugabe's 33-year rule.

Tsvangirai's allies announced on Monday that they will launch a constitutional court challenge against the results of Wednesday's election, which handed Mugabe 61 percent of the vote.

"Our lawyers are very busy at work. We will be lodging the presidential challenge before Friday," Douglas Mwonzora, spokesman for Tsvangirai's Movement for Democratic Change (MDC), told the AFP news agency.

Our lawyers are very busy at work. We will be lodging the presidential challenge before Friday.

Douglas Mwonzora, MDC spokesperson 

The case could delay 89-year-old Mugabe's inauguration for another five-year term.

The MDC had support from the US and European nations condemning the election, and Australia even calling for a re-run.

The regional Southern African Development Community (SADC) bloc said it was "free and peaceful" but stopped short of describing it as fair.

'Dossier of all rigging'

The ruling ZANU-PF has welcomed the prospect of a court challenge over the vote - the first since bloody 2008 elections led to the formation of an uneasy power-sharing pact between Mugabe and Tsvangirai.

"What they are doing is a good thing, it's a wise road to take," ZANU-PF spokesman Rugare Gumbo said, expressing confidence the challenge would fail.

Mwonzora said the MDC was preparing a "dossier of all the rigging that took place and we will put it in the public domain to show the people how the election was stolen".

The MDC has called for an emergency summit of SADC after the group gave the vote a thumbs-up, but deferred on calling the election "fair".

The MDC also took a hammering in the parliamentary vote, winning just 49 seats out of the 210 up for grabs - down more than half from its 2008 performance - against 160 for Mugabe's party.

Source: Agencies