Berlin - German chemicals concern BASF, the world's largest company in the sector, made a cash offer on Monday for Swiss rival Ciba, valuing the company at 3.8 billion euros (5.4 billion dollars).

BASF Chief Executive Juergen Hambrecht said the offer of 50 euros a share, equivalent to a premium of around 30 per cent on Ciba's Friday close, was final.

The German company aims to enhance its presence in the speciality chemicals sector through the purchase.

Hambrecht said that the sector for chemicals used in paper making was in need of restructuring.

Ciba's board welcomed the offer and said it would recommend it to shareholders. BASF had agreed to maintain key production centres in Switzerland, Ciba management board head Armin Meyer said.

The offer is to run for 30 days from October 1.

Ciba, which employs around 13,000 staff, posted turnover of 4 billion euros in 2007, by comparison with BASF's 57.9 billion euros. The German company employs 95,000 workers. (dpa)