Spain's Bankinter has partnered with American investment fund Apollo Global Management to bid for Swiss private bank BSI in an up to 2 billion euro deal, according to three sources familiar with the matter.

BSI is being sold by its owner, Italian insurer Generali, in a move to free up 4 billion euro capital from non-core assets in compliance with new rules for insurers in Europe.

Two of the people knowledgeable with the deal said that BSI's takeover is also being sought by the banks Brazil's Safra and its Chinese rival ICBC.

BSI and General did not response to the speculated deal. Representatives of Bankinter and Apollo were also not available to comment.