He did not elaborate on when the petrochemical maker will be able to receive naphtha at its 1.1 million tonne-per-year Daesan naphtha cracker where the explosion took place. It has another 1.2 million tonne-per-year cracker in Yeosu which is operating normally. [O/ACRACKER]

"We have told (the suppliers) that we're not in a situation to be able to receive (the) naphtha cargoes following the explosion," the spokesman said, adding that the volumes comprise of imported and domestic cargoes.

Hyundai Chemical, a joint venture between Hyundai Oilbank and Lotte Chemical, supplies some 1 million tonnes of light naphtha a year to Lotte Chemical.

Industry sources said the loss of demand from Lotte Chemical has impacted the market in a matter of days following the explosion, although it has improved but this would be short-lived.

The intermonth spread -- the price differential between front-month second-half April prices against that of second-half May -- flipped into a discount on March 9 for the first time since September. But it has since returned to a $6 a tonne premium on March 11 versus this year's peak on Jan. 28 at $24.

"Prompt supplies are still tight due to refinery maintenance in the Middle East," said a source who tracks naphtha.

But in May the naphtha market could be hit as refineries in the Middle East -- top naphtha supplier to Asia -- will return from maintenance.

Separately, Lotte Chemical declared force majeure on petrochemical products supplies including ethylene to its key customers last week after the explosion, the spokesman said.

"We have informed our major clients of supply disruptions after an explosion last week and told them that we will do our best to find ways to supply products and to resume operations," the company spokesman said.

(Reporting by Jane Chung and Seng Li Peng; editing by Jason Neely)