Vodafone to boost Ghana investment to $700 million

* Post-deal investment will rise to $700 million

* Critics of Ghana Telecom sale now in power

ACCRA, May 11 (Reuters) - British mobile phone company Vodafone Group (VOD.L: Quote, Profile, Research) will invest $200 million more than originally planned in its Ghana Telecom unit, taking total expected investment to $700 million, it said on Monday.

Vodafone spent $900 million on a 70 percent stake in the Ghanaian firm last August, a deal which had been hotly debated in the West African country's parliament. It initially signalled it would then invest $500 million over five years.

The then opposition party, John Atta Mills's National Democratic Congress (NDC), which took power in January after narrowly winning elections, has said the process leading up to the deal was not transparent and critics said it underpaid.

"We decided to increase the investment in order to effectively improve network quality and undertake quality expansion," said Ben Padovan, Vodafone spokesman in Ghana.

The company told a Ghanaian government delegation led by President Mills which visited Britain last week it intended to increase its investment, he said.

He declined to comment on the possibility of Mills's government reviewing the original deal. "All I can say is that we had a good meeting with the President over the issues."

One of the NDC's chief critics of the deal, Haruna Iddrisu, is now Communications Minister. (Reporting by Kwasi Kpodo; Editing by Daniel Magnowski and Dan Lalor)