(Reuters) -- Italian insurer Unipol said on Sunday it has agreed to a four-way merger plan to rescue insurance company Fondiaria-SAI with its parent company Premafin .

Under the planned deal, which also includes Fondiaria's unit Milano Assicurazioni , Unipol would launch a capital increase of up to 1.1 billion euros ($1.44 billion), Unipol said in a statement.

Premafin, which owns 35.7 percent of Fondiaria-SAI, is expected to launch its own capital increase of up to 400 million euros reserved for Unipol.

Unipol's subscribing to the Premafin capital increase is subject to the regulator's approval, go ahead from the antitrust and exemption from any mandatory bid on the shares of Premafin, Fondiaria-SAI and Milano Assicurazioni

Unipol said it expected the four-way merger to be completed by the end of 2012.

(Reporting by Svetlana Kovalyova)