* Delays at some polling stations, Biya urges patience
* Opposition cites evidence of double voting
* Biya tipped to win in single-round poll (Adds end of voting, edits)
By Tansa Musa
YAOUNDE, Oct 9 (Reuters) - Voters in Cameroon faced delays and organisational shortfalls in an election on Sunday where President Paul Biya is expected to extend his 29-year rule over the central African state against a fragmented opposition.
The one-round vote comes just weeks after a smooth handover of power in Zambia showed that Africa can deliver peaceful political change through the ballot box.
But with Biya, 78, seen keeping his place among the clutch of African leaders in power for decades, the main question in the oil-producing nation is whether the election will pass smoothly after rivals alleged the vote is skewed against them.
There were no official turnout figures but voting appeared sluggish in the capital Yaounde. Many Cameroonians appeared indifferent to the election campaign, feeling the vote was a foregone conclusion. Results could take days to emerge.
"It is a disgrace that many Cameroonians did not register and even the few who did would not come out to vote," 53-year-old secondary schoolteacher Bernard Ojong said.
"When we don't vote how do we ever expect things to change? This is very frustrating."
Election observers said voting was peaceful but cited delays at some polling stations and irregularities such as some voters being allowed to jump the queue.
After voting ended, a Reuters reporter in Yaounde saw 19 polling stations where ballots were being counted without the required presence of candidates' representatives.
"Some polling stations opened late, some appeared unclear on the rules about how votes are cast," Commonwealth observer mission leader Frederick Mitchell said by telephone.
Biya's main rival John Fru Ndi of the Social Democratic Front (SDF) said a surplus of voting slips meant some had voted twice in certain parts of the country and said election body Elecam would be blamed for the "disorder and confusion".
Casting his vote in Yaounde, Biya asked for patience.
"It (Elecam) is a young organisation ... I'm just asking that there should be indulgence in any eventual imperfection. There was no intention to fraud," he said.
Aside from its oil, Cameroon is the region's main maritime entry point and breadbasket, supplying Chad, Central African Republic, Congo Republic and Gabon. It hosts the Chad-Cameroon pipeline and shelters refugees from the region's conflicts.
Biya faces 22 candidates including Fru Ndi, and Adamou Ndam Njoya of the Cameroon Democratic Union (UDC).
In the last election in 2004, Biya scored just over 70 percent, while his closest rival, Fru Ndi, took 17 percent.
"BELOW POTENTIAL"
In 2008 a move by Biya to scrap term limits, and anger over food prices, led to street protests in which more than 100 people died, but for most of the past three decades there has seen relative stability in a turbulent region.
However, one issue which has not gone away is a separatist movement in the south and last week security forces detained more than 200 people after they held a banned rally calling for the right to secede.
Biya's goal is to set Cameroon on the path to being an emerging nation such as Mexico and Malaysia by 2035.
Yet Cameroon's media and opposition have criticised Biya for lax governance, allowing corruption, red tape and nepotism to fester. Average income per head stands at an annual ${esc.dollar}2,000 -- higher than most of the region -- but the IMF has described its forecast 3.8 percent growth this year as below potential.
Some observers speculate that Biya, if reelected, will use his new term to arrange a handover of power to an anointed successor. But his domination of the local political scene means there is currently no obvious candidate for that.
A ban on the announcement of preliminary results means it could take days for the final tally to be published. (Additional reporting by Bate Felix in Dakar; writing by Mark John; editing by Maria Golovnina)
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