BASF is preparing to divest "major parts" of its nitrogen fertilizer business, which is under pressure from low-cost producers in the Middle East.

BASF, the world's largest chemical company by sales, said on Tuesday that the operations it is putting on the block account for less than 1% of BASF's group annual revenue, which would be less than €640 million ($885 million).

The businesses, with a combined annual capacity of about 2.5 million tons of fertilizer, comprise plants in Antwerp, Belgium, and BASF's 50% share in its PEC-Rhin joint venture with France's Total.

German fertilizer producer K+S AG said it is looking at a part of the operations put up for sale.

"We are evaluating if a purchase could make sense," a spokesman for K+S told German daily Frankfurter Allgemeine Zeitung in a pre-release of Wednesday's edition.

BASF did not name prospective buyers but said it plans to complete the transaction by the first quarter of 2012.

German potash fertilizer specialist K+S, in which BASF holds a 10% stake, in 2000 agreed to market BASF's nitrogen products, but the business is grappling with low-cost rivals.

Middle Eastern chemical companies such as SABIC, are using their cheap access to natural gas, the feedstock needed for nitrogen, to boost their fertilizer businesses.

BASF added it would not sell the nitrogen plants at its Ludwigshafen, Germany, headquarters because they are too closely tied with its other operations.