The African Development Bank will contribute $500 million towards the financing of a new airport in Ethiopia, which is expected to be Africa's largest when completed in 2029, it said on Monday.

State-owned Ethiopian Airlines has signed an agreement for the design of the four-runway airport near the town of Bishoftu, around 45 km (28 miles) southeast of the capital, Addis Ababa.

The airline has said it will provide 20% of the funding for the $10 billion project, and the rest will come from creditors.

"The bank has itself earmarked up to $500 million, subject to board approval, to anchor the funding of this transformational regional integration project," the development bank said in a statement.

Last week, it said it was leading efforts to raise $7.8 billion for the project, which will have the capacity to handle 100 million passengers per year.