NEW DELHI (Reuters) - Pranab Mukherjee, a former finance minister of India and senior leader of the ruling Congress party, has been elected as the new president, a government official said on Sunday.

On Thursday, India's 4,896 lawmakers in state assemblies and parliament cast their votes for the president, a ceremonial post.

"I declare that Pranab Mukherjee has been duly elected to the office of the president," V.K. Agnihotri, returning officer for the poll, told reporters. Mukherjee, who got more than 700,000 votes, had only one opponent without much support.

Prime Minister Manmohan Singh assumed the additional portfolio of acting finance minister in June, replacing Mukherjee when he resigned to run for president.

Many analysts believe the finance ministry will be an opportunity for Singh to overcome policy inaction and initiate a slew of reforms to help the faltering economy.

Mukherjee, 76, could also play an important role if one political party fails to get a clear mandate in the next general elections due by 2014.

(Reporting by Nigam Prusty; editing by Mayank Bhardwaj and Mark Heinrich)