* Opposition accused Mahama of rigging poll
* Observers said voting was free and fair
* Mahama promises unity, development
By Kwasi Kpodo
ACCRA, Jan 7 (Reuters) - Ghana’s opposition boycotted the inauguration of President John Dramani Mahama on Monday, ignoring his appeals to end a dispute over last month’s election in the West African state seen as a model democracy in the coup-prone region.
Mahama, who narrowly defeated his rival Nana Akufo-Addo in a Dec. 7 vote, pledged to focus on development and unite Ghanaians.
“There is a tremendous amount of work that still needs to be done. More jobs must be created. More roads must be built,” Mahama, dressed all in white, told cheering crowds in the capital Accra.
Ghana became Africa’s newest oil exporter in 2010 with the startup of Tullow Oil’s offshore Jubilee field, propelling economic growth to 14.4 percent in 2011.
That rise has not been reflected in average incomes in the cocoa and gold exporter.
Ajufo-Addo’s opposition New Patriotic Party (NPP) accused Mahama - a former vice president who took office in July after the death of President John Atta Mills - of rigging the Dec. 7 poll.
The NPP said it was pushing ahead with a legal challenge to the election results.
“We have filed an action at the Supreme Court seeking to overturn the declaration of results so we don’t want to be part of any event which is based on those results,” said Nana Akomea, the party’s director of communication.
International observers said the election was free and fair despite delays and technical problems that forced voting into a second day.
Mahama won the ballot with 50.7 percent of the vote to Akufo-Addo’s 47.7 percent, just enough to avoid a second round.
Former-president John Kufuor, an NPP member, did attend the ceremony, defying the boycott and a group of young party members who gathered outside his house to persuade him not to go.
South African President Jacob Zuma and Nigeria’s Goodluck Jonathan joined other African leaders at the ceremony in the seafront Independence Square.
Earlier, a new parliament dominated by the ruling party took office and elected its speaker and deputies.
Ghana is one of Africa’s fastest growing economies and has maintained three decades of peace, making it a favourite among international investors and an anomaly in a region better known for revolts and civil wars. (Reporting by Kwasi Kpodo; Editing by Daniel Flynn and Andrew Heavens)