FACTBOX - Three leading candidates in Cyprus vote

(Reuters) - Half a million Greek Cypriots vote on February 17 for a new president in a hotly-contested election which is expected to move to a second round run-off on February 24.

Nine candidates are in the running, with chances of victory almost equally split between incumbent Tassos Papadopoulos, communist challenger Demetris Christofias, and right-wing backed Ioannis Kassoulides.

Following is a brief profile of the three key candidates:

Tassos Papadopoulos, 74

British-trained lawyer and constitutional expert, won presidency with 51.5 percent of the vote in February 2003. Led Greek Cypriots into rejection of a United Nations reunification blueprint for the divided island in April 2004, a week before island joined European Union.

Opponents say he is a hardliner who failed to take any decisive initiative to break logjam in reunification talks. Papadopoulos says key to reunification lies with Turkey. His poll standing is between 30.5 and 32.5 percent.

Demetris Christofias, 62

Soviet-educated, spent most of his adult life in various posts in AKEL, the island's communist party which he now leads as secretary-general. Helped Papadopoulos win election in 2003 and AKEL was senior partner in incumbent's administration. Relations soured in 2007, when Papadopoulos refused to back Christofias in bid for presidency.

Christofias has since accused Papadopoulos of failing to be pro-active in seeking reunification of the island. He is currently marginally behind Papadopoulos in opinion polls with between 30.15 and 31.8 percent of vote.