Dr Abdullah Abdullah with Dr Ashraf Ghani.(Reuters)
Afghan election contender Abdullah Abdullah on Thursday congratulated President-elect Ashraf Ghani on his victory and vowed to support him in a national unity government.
Election officials on Sunday named Mr Ghani as the winner, but declined to release the margin of victory or the turnout triggering accusations that the result lacked transparency.
Mr Ghani and Mr Abdullah Abdullah struck an agreement on Sunday to form a "unity government", after months of disputes over who was the rightful winner of the fraud-tainted June 14 presidential election.
In the "national unity government", Mr Ghani will become president and Abdullah will serve as chief executive, a new role similar to prime minister.
"I want to congratulate Dr. Ashraf Ghani the future president of Afghanistan and thank him for his stance on the political deal for creating a national unity government," Mr Abdullah said addressing a big gathering of his supporters.
"The political deal that results in the creation of the national unity government is the best alternative and best choice for the people of Afghanistan," he said.
"If you see the current situation of Afghanistan, there is no better alternative," he said.
"This national unity team, God willing will join hands and cooperate" he added.
The two men must now govern Afghanistan as international funding declines and US-led combat troops pull out by the end of this year after fighting the Taliban since 2001.
The chief executive could become the official prime minister in two years' time, a major change to the strongly presidential style of government laid out in the constitution.
Coalition relations could prove tricky after the two campaigns traded allegations of ballot-box stuffing in the race to succeed President Hamid Karzai, who will hand over power at an inauguration ceremony next week.
The unity government paves the way for a Bilateral Security Agreement (BSA) governing the presence of American troops in Afghanistan beyond 2014, which Mr Karzai had refused to sign.
About 41,000 NATO troops remain in Afghanistan fighting the fierce Taliban insurgency alongside Afghan soldiers and police.
NATO's combat mission will end in December, with a follow-on force of about 12,000 troops likely to stay into 2015 on training and support duties.