Indian refiners have turned to State Bank of India and Germany-based bank Europaeisch-Iranische Handelsbank AG (EIH) to speed payment of billions of Iranian oil dues they still owe to Tehran, after delays in another money route, Reuters reported.

Since that the lift of sanctions has opened up oil trade channels with Tehran, Refiners in India –, Iran’s top oil buyer after China– have settled their back debt that amounts at $6.6b.

According to Live Mint, the Union Bank of India handled the first payments last May through Turkey’s Halkbank. The Union Bank had also handled payments before sanctions were imposed on Iran back in 2013. Yet, it has requested the refiners to raise the credit limits or deposit money in rupees one day before beginning payments. On their side,  refiners were fearful of delays in working down their oil debt.

A senior official at the Union Bank of India confirmed that his bank was no longer handling Iran oil payments as refiners are taking the lead in settling the dues , in efforts to wipe out their debt in three months limit set by the Reserve Bank of India. India has limited weekly dollar purchases by oil refiners at $500m as they pay off their Iran debts to avoid pressure on the rupee.