BASF to cut 3,700 jobs as part of Ciba takover

* To close or sell up to 23 of 55 Ciba sites

* Aims for 400 mln eur in annual synergies

* Sees 500 mln eur in total cash expenses from integration

* Shares up 0.1 percent

(Adds details, background)

FRANKFURT, July 6 (Reuters) - BASF (BASF.DE: Quote, Profile, Research, Stock Buzz) plans to cut 3,700 jobs as part of the integration of Swiss rival Ciba and may sell or close as many as 23 of Ciba's 55 sites, it said on Monday.

That is the equivalent of around 28 percent of Ciba's 13,000-strong headcount, but some cuts will affect BASF staff, a spokeswoman said.

In its first detailed statement on the repercussions of the takeover, BASF said it aimed to generate synergies of at least 400 million euros ($559.1 million) per year from 2012 and that by the end of next year savings should amount to approximately 300 million euros.

"The combined businesses can be successful in the long term only if we optimise them and exploit the full potential for synergies," Chief Executive Juergen Hambrecht said.

The integration will cost 550 million euros in cash, about 150 million euros of which will be incurred in 2009, the world's largest chemical maker added.

BASF said it would disclose details of further non-cash integration costs along with second-quarter results on July 30.

The company, which agreed to buy Ciba for 3.4 billion Swiss francs ($3.13 billion) a few months before global chemical demand collapsed last year, aims to carry out most of the job cut by 2013 and decide on which sites to shutter or sell by the end of the first quarter of 2010.

BASF has started talks with employee representatives on the cutbacks, it added.

Its shares were little changed after the statement and traded up 0.1 percent at 27.7 euros.

(Reporting by Ludwig Burger and Frank Siebelt)