FACTBOX: What next in Zimbabwe's elections?

(Reuters) - Below are answers to some key questions as counting continues after Zimbabwe's elections, in which President Robert Mugabe faced an unprecedented challenge to his 28-year rule.

WHAT DO THE RESULTS SHOW?

Not much so far. Only a few parliamentary results have been issued by the electoral commission, under pressure to explain a delay that has fuelled accusations of rigging.

First parliamentary constituency results were evenly split between Mugabe's ZANU-PF and the opposition Movement for Democratic Change (MDC). However the opposition says its own unofficial count shows it with 60 percent of the presidential vote and 96 out of 128 known seats. There are 210 parliamentary constituencies.

Analysts say early counting tends to come from the opposition's urban strongholds whereas later results will include rural areas that are Mugabe's traditional base.

WHY ARE DELAYS SIGNIFICANT?

In past elections, results emerged quickly. The electoral commission says it is more complicated now because presidential, parliamentary and local elections were held together for the first time.

Further delays would stoke opposition suspicions of rigging to ensure the continued rule of Mugabe, blamed by opponents for an economic crisis that has ruined Zimbabwe. He blames Western sanctions. Analysts say delays increase the danger of rumors and violence.

"In a polluted environment, as you find in Zimbabwe, of polarization and suspicions that there could be attempts to rig the elections, minor issues such as the delay in the results fuel suspicion that what many people had in mind is indeed being confirmed," said Siphamandla Zondi of South Africa's Institute for Global Dialogue think-tank.

HOW DID VOTING GO?

There were no major reports of violence in Saturday's vote but the opposition and one African observer group reported irregularities -- including rolls with many non-existent or dead voters.

The main observer team from regional bloc SADC, long seen as being soft on Mugabe, said the vote looked free and fair but two members from South Africa's main opposition party dissented and refused to sign a preliminary report.

Most international observers were banned.

WHO WILL WIN?

Morgan Tsvangirai's opposition MDC says it won based on local vote counts pinned up outside polling stations. The government has warned such premature declarations could amount to "a coup".

Many analysts expect the result to be manipulated and said Mugabe would declare victory even if he lost. Security service chiefs have said they would not accept an opposition win. Tsvangirai and some international observers said Mugabe lost the last presidential election in 2002 but he stayed in power.