(Adds details on financing components)
ACCRA, Dec 15 (Reuters) - The World Bank Group said on Thursday it two of its units would provide another $517 million to Ghana in debt and guarantees to support the $7.7 billion Sankofa oil and gas project developed by Italy's ENI SpA and upstream trader Vitol Ghana.
The financing adds to a $700 million World Bank guarantee package announced in July and brings the institution's total financing to around $1.217 billion for the offshore project, whose gas component is set to open in 2018, a statement said.
The bank's commercial lending arm, the International Finance Corporation (IFC), has committed a loan of $235 million to Vitol Ghana and is arranging another $65 million in debt.
Guarantees by the Multilateral Investment Guarantee Agency, another bank institution, will support Vitol Ghana's commercial borrowing needs for the project and will be issued for up to 15 years. The new pledges bring the World Bank Group's financing share of the Sankofa project to about 16 percent.
"Sankofa is expected to generate $2.3 billion in revenues for Ghana's government per year and provide a stable, long-term source of domestic gas that will solve Ghana's chronic gas supply constraints," an IFC statement said.
ENI holds a 44.4 percent stake in Sankofa, Vitol holds 35.6 percent and Ghana National Petroleum Corporation holds a combined carried and participating interest of 20 percent.
Ghana first began pumping oil in 2010 at the offshore Jubilee field operated by Tullow Oil Plc, a British company that this August opened a second field called TEN.
Sankofa is expected to generate about 1,000 megawatts of power for Ghana and, combined with gas from two other new fields, could eliminate the need for Ghana to import gas from Nigeria through the West African Gas Pipeline Co. (Additional reporting by David Lawder; Writing by Matthew Mpoke Bigg; Editing by James Dalgleish and Jonathan Oatis)