* Veteran politician seeking presidency for third time
* Akufo-Addo lost legal challenge after 2012 vote
ACCRA, March 20 (Reuters) - Ghanaian President John Mahama's main rival in the last election, Addo-Dankwa Akufo-Addo, said on Thursday he would run again in 2016 as a candidate for the main opposition party.
Presidential elections in one of Africa's fastest growing economies have for decades been a two-horse race between Mahama's National Democratic Congress and the New Patriotic Party. Mahama is also widely expected to run for re-election although he has not formally confirmed it.
"I can announce that when the party opens nominations sometime this year, I shall be ready, God willing, to contest for the position of the NPP presidential candidate for the 2016 general elections," Akufo-Addo, 69, told journalists at an event where supporters danced and sang popular party songs.
This would be Akufo-Addo's third attempt at the presidency after also losing in 2008 to John Atta Mills.
In 2012, he came second to Mahama with 47.4 percent of the vote and later filed a challenge to the Supreme Court, saying his party had evidence to show there were enough irregularities to affect the outcome.
The court affirmed Mahama's victory, saying irregularities cited by the NPP were not sufficient to alter the outcome. (Reporting by Kwasi Kpodo; Editing by Emma Farge/Mark Heinrich)