Exploration and production group Tullow Oil has extended its $3.5 billion debt facility by four years to 2019.

Tullow had an existing agreement with its bankers allowing it to borrow up to $3.5 billion which was due to expire in 2015.

It has not drawn down this amount and its net debt is currently $695 million.

The Irish group said yesterday it has replaced it with a new agreement with a syndicate of 27 international lenders that expires in November 2019.

The new facility allows Tullow to borrow up to $3.5 billion. This is made up of a senior facility of $3.235 billion and a junior facility of $100 million.

The International Finance Corporation, a division of the World Bank that lends to projects in developing countries, committed up to $165 million. Along with this, the group has the option of increasing the senior loan facility by up to $500 million.

The group said yesterday 27 international banks signed up to the new agreement last week.

The offer was oversubscribed, meaning the Irish company was offered more debt than it sought. The lead banks include BNP Paribas, Bank of America, Barclays Bank, Deutsche Bank, HSBC, Lloyds TSB and Royal Bank of Scotland.

Tullow’s biggest oil-producing asset is the Jubilee Field off Ghana, due to deliver about 90,000 barrels a day by the end of the year.

Tullow has a range of licences across Africa and south America in various stages of development.