Petroliam Nasional Bhd, Malaysia's state oil company, increased a price-adjustment factor for its flagship Tapis crude to a record high for a second month as profits from making diesel rose.

Petronas, as the Kuala Lumpur-based company is known, set the so-called alpha at US$9.50 a barrel for April, an official said today, asking not to be identified because of internal rules. It was US$8.65 for March and averaged US$5.90 in 2011.

Tapis is refined mainly for gasoil, or diesel. The product's premium to Asian benchmark Dubai crude has climbed 2.5 per cent so far this month after a 2.2 per cent gain in March, according to data from PVM Oil Associates Ltd, a London-based broker. The so-called gasoil crack spread was at US$15.88 a barrel at the end of trading yesterday.

Petronas includes the Tapis adjustment factor in its monthly calculations of official selling prices. The formula is tied to Brent produced in the North Sea, a benchmark grade for Europe, the Mediterranean and Africa. -- Bloomberg