LONDON (Reuters) - Ex-Barclays (>> Barclays PLC) boss Bob Diamond has poached a former senior colleague from the British bank to head Atlas Mara (>> Atlas Mara Co-Nvest Ltd), a venture he wants to build into the leading bank in sub-Saharan Africa.

Atlas Mara said on Tuesday it had appointed former U.S. marine John Vitalo as chief executive officer.

Vitalo has been chief executive of Barclays' Middle East and North Africa region since May 2009, and in the previous four years was responsible for building and leading Absa Capital, Barclays' African investment bank arm.

Atlas Mara has said it wants to become Africa's leading financial services firm by providing capital, liquidity and funding to banks in sub-Saharan Africa.

The company is backed by Diamond and Africa-based billionaire entrepreneur Ashish Thakkar, and raised $325 million (195 million pounds) in a London listing in December. Diamond and Thakkar have invested about $20 million between them.

Atlas last week bought BancABC, which has operations in Botswana, Mozambique, Tanzania, Zambia and Zimbabwe, for up to $265 million in cash and shares, and this week said it planned to buy a controlling stake in state-run Development Bank of Rwanda.

The deals mark a return to the spotlight for Diamond, the high-profile American banker who was ousted from Barclays in 2012 after the bank was fined $450 million for rigging Libor interest rates.

Barclays was the first bank fined for interest rate manipulation, but since then UBS (>> UBS AG), Royal Bank of Scotland (>> Royal Bank of Scotland Group plc) and Rabobank have been handed bigger fines and other banks have been fined for rigging Euribor rates.

Diamond built up Barclays' investment bank into a global power over more than a decade, but since he left it became clear he had a poor relationship with regulators who said he had "sailed too close to the wind" after taking over as group chief executive at the start of 2011.

He sees scope for strong potential in banking in Africa, where Barclays and Standard Chartered (>> Standard Chartered PLC) also predict strong growth. Barely a quarter of sub-Saharan Africans have a bank account, yet economic growth in the region is set to outpace the global average over the next three years, according to World Bank figures last year.

Vitalo joined Barclays in 2002 from Credit Suisse (>> Credit Suisse Group AG), where Diamond also used to work. Vitalo will be responsible for directing and executing the company's strategy and will lead an executive committee that includes Doug Munatsi, CEO of BancABC, and Jyrki Koskelo, the company's head of strategy.

Barclays was not immediately available to comment.

(Editing by John Stonestreet)

By Steve Slater