UPDATE 3-Namibia votes, ruling party set to retain power

* Ruling party expected to win by comfortable margin

* Breakaway faction may become official opposition

(Adds details, ECN comment)

By Agnieszka Flak

WINDHOEK, Nov 27 (Reuters) - Namibians voted on Friday in presidential and parliamentary elections likely to hand President Hifikepunye Pohamba five more years in power, but with a new opposition threatening his party's two-thirds majority.

Polls close in the two-day vote at 1900 GMT on Saturday, with first results expected a few hours later, but it may take until Wednesday for a final announcement.

The Rally for Democracy and Progress (RDP), which broke away from the ruling SWAPO party in 2007, is expected to become the official opposition, replacing the Congress of Democrats.

Rich in resources and wedged between economic powerhouse South Africa and oil-producing Angola, Namibia has enjoyed a long period of political and economic prosperity that has made its 2.2 million people the envy of many in Africa.

"SWAPO will still win with a comfortable margin, but we are likely to have a new opposition party, targeting SWAPO's traditional strongholds," said Graham Hopwood, director of the Institute for Public Policy Research (IPPR) in Windhoek.