FRANKFURT, Aug 28 (Reuters) - Abu Dhabi National Oil

Company (ADNOC) is finalising due diligence for a takeover of

Covestro ( CVVTF ) in a deal that could reach 11.7 billion euros

($13 billion), two sources familiar with the matter told Reuters

on Wednesday.

An announcement could come in September as the process

enters its final phase, with a price of 62 euros per Covestro ( CVVTF )

share still on the table, the sources said.

Covestro ( CVVTF ) and ADNOC declined to comment. Bloomberg first

reported the news on Wednesday.

Covestro ( CVVTF ) shares rose as much as 5.7% to 56.90 euros,

reaching their highest level in almost three years.

The Leverkusen-based plastics company announced at the end

of June that it would enter into concrete negotiations with

ADNOC. After months of canvassing, the oil company announced a

possible offer of 62 euros per share, subject to due diligence.

Covestro ( CVVTF ) finance chief Christian Baier told Reuters at the

end of July that there had been progress in the talks and that

the negotiations were continuing to be very constructive.

Covestro ( CVVTF ) is the former plastics subsidiary of Bayer

, which the pharmaceutical and agricultural group took

public in 2015.

The company employs around 17,500 people worldwide, with

almost 7,000 in Germany. Covestro ( CVVTF ) manufactures intermediate

products for the automotive, furniture, household appliance and

construction industries. Its products can be found in mattress

foam and car seats, as well as in wind turbine blades.

($1 = 0.9001 euros)