The offer of 825 pesetas per share in cash represents a premium of 25 per cent over the share price on 16 April.
The UK parent has already won agreement from the largest minority shareholder to accept the offer in respect of his 4 per cent stake. Barclays expects approval from the deal from the Spanish Securities Commission within the next 10 days.
There are about 5,000 smaller shareholders, who have a month to accept the offer.
The Spanish operation was set up in the mid-1980s and was the first to introduce interest-bearing current accounts to Spain. It has 225 branches and contributed pounds 18m to group profits last year.
Shares in the subsidiary were listed in 1987. A Barclays spokeswoman said that since then the downturn in the Spanish stock market had damaged the shares' liquidity, and that Barclays' desire to operate only through wholly-owned subsidiaries made the buy-in 'an appropriate tidying-up job'.
Last week Barclays announced the closure of its Leeds-based Barclays Direct mortgage subsidiary, which sold loans through insurance companies. It had about 40,000 customers whose loans were already administered by the division that looks after loans sold through branches.Reuse content