Saudi Aramco and the US’ Dow Chemical, the partners behind the $19.3bn Sadara Chemical project, have signed the $12.5bn debt financing for the scheme.

The deal is expected to be the largest project finance transaction in the world this year.

According to sources involved in funding the project, the debt is split between a $5bn US Exim loan, a $2bn sukuk, and about $2bn of commercial bank lending, of which about $1.1bn is coming from US banks lending in dollars, with the rest coming from local currency loans from the Saudi banks.

Banks were first approached to lend on the deal in the first half of 2012. Many say they are relived it has finally been closed after waiting for so long for the transaction to be signed.

The financing also features a $1.3bn loan from the Saudi government-owned Public Investment Fund. A further $1.8bn is coming from export credit agencies (ECAs) including $700m from the UK’s Export Credits Guarantee Department (EGCD), $500m from South Korea’s K-sure, and $425m from Germany’s Hermes.

The UK’s Royal bank of Scotland and the local Riyad Bank were financial advisers to Aramco and Dow.

With the Sadara deal now completed, Aramco is now expected to shift focus to PetroRabigh 2, a $7bn joint venture of the Saudi oil company and Japan’s Sumitomo Chemical Company. “Aramco has indicated that it wants to move quite quickly on the funding for PetroRabigh 2 once Sadara is out of the way,” says one banker in the kingdom.