Companies bidding for the engineering, procurement and construction (EPC) contract to build the 125,000-tonne-a-year butene-1 plant are understood to include Japan's Toyo Engineering Corporation, South Korea's Samsung Engineering Corporationand the US' Mustang Engineering.

Technical bids for the estimated $40 million-50 million project were submitted in early April.

The plant will complement the two butene-1 units, each with capacity of 50,000 t/y.

The Petrokemya complex, which started production in 1985, also comprises three olefins units, producing ethylene, propylene, polystyrene and butadiene.