SINGAPORE (Reuters) – Saudi Aramco’s trading arm bought 70,000 tonnes of naphtha from Indian Oil Corp on Friday at premiums not seen since 2013 as it seeks to plug a supply gap following Sept. 14 attacks on its facilities, trade sources said on Monday.

Aramco Trading Company (ATC) paid a premium to IOC price formula on a free-on-board basis in the mid-$40 per tonne range for a 35,000-tonne cargo scheduled for Oct. 18-20 loading from Chennai and for a 35,000-tonne cargo for Nov. 3-5 loading from the same port.

These were the highest premiums IOC has fetched for naphtha sold out of Chennai since it sold a cargo to Unipec at a premium of about $55 a tonne in 2013, Reuters data showed.

Since the attacks, ATC has bought more than 120,000 tonnes of naphtha from Europe and about 130,000 tonnes from India, including the latest purchase from IOC and a previous deal with Hindustan Petroleum Corp Ltd.

It also has cargoes from Egypt but these were mostly locked in before the attacks.