UPDATE 1-IOC seeks more April sweet crude in tender

(Releads, adds new tender, details)

LONDON/NEW DELHI, Feb 13 (Reuters) - India's largest state-owned refiner, Indian Oil Corp (IOC), issued its third tender for April loading sweet crude on Friday, the same day it bought 4 million barrels of Nigerian crude, traders said.

Grade offers for the tender are due on Wednesday with prices required by Thursday and the result is expected to emerge on Friday.

IOC bought two Very Large Crude Carriers (VLCC) of Nigerian crude oil in its second tender for April loading, which ended on Friday.

The purchase was made up of one VLCC, or around 1 million barrels each of Qua Iboe QUA-BFO and Amenam grades from commodity trading company Trafigura, and one VLCC of Qua Iboe from Vitol, traders said.

The Amenam cargo was traded for about dated Brent plus $3.30, while Trafigura's Qua Iboe cargo sold for around dated Brent plus $3.20, a trader said. This was not confirmed.

A trader said the Qua Iboe from Vitol was traded at around dated Brent plus $3.00, but this was not confirmed.

Differentials for Qua Iboe, one of Nigeria's benchmark grades, have widened in the last month due to improving gasoline refining margins and tightening of supplies.

IOC bought one VLCC, or 2 million barrels, of Nigerian Bonny Light BON-BFO and Bonga grades from oil major Royal Dutch Shell (RDSa.L: Quote, Profile, Research) and 1 million barrels of Azerbaijan's Azeri Light in its first tender for April.

However, the delivery of IOC's Bonny cargo is in doubt after Shell said on Thursday it had declared force majeure on its Bonny Light shipments due to insecurity in the Niger Delta. [ID:nLC815941]

IOC issued three tenders for March, buying mostly West African crude as improving refining margins and a tightening of supply raised demand for Nigerian and Angolan grades. (Reporting by Joe Brock and Nidhi Verma in New Delhi; Editing by Anthony Barker)