UPDATE 1-Allianz preparing Swiss Life offer-French website

(Updates with Swiss Life)

PARIS Jan 10 (Reuters) - German insurer Allianz (ALVG.DE) is preparing an offer for Swiss Life (SLHN.VX), French website Wansquare reported on Sunday, citing various Swiss banking sources.

If an offer materialises in the coming days, it would be based on 5.5 billion Swiss francs ($5.3 billion), given Swiss Life's market value of 4.6 billion francs and a minimum premium of around 20 percent, Wansquare said.

A spokesman for Allianz declined to comment on the report. A spokesman for Swiss Life also declined to comment.

Shares in Swiss Life rose last week as traders pointed to speculation that Allianz could be interested in making a bid for the company. Allianz Chief Financial Officer Oliver Baete said in November that Allianz had no plans for either acquisitions or a capital increase. The group has a market value of 40 billion euros ($57 billion). ($1=1.033 Swiss Franc) ($1=.6983 Euro) (Additional reporting by Eva Kuehnen in Frankfurt; Writing by James Regan, editing by Maureen Bavdek)