Club coach Ewald Lienen said the defender would stay until the end of the season to help bail out the relegation-threatened side.

Cologne currentlly lie second bottom in the Bundesliga having concede 25 goals in 13 games.

"He is a pacy and very aggressive player and his arrival will benefit us," said Lienen.

Song has failed to secure a regular first-team shirt at English Premiership club West Ham since since a �2.5 million switch from Liverpool last November.

He last played for West Ham in their 5-0 defeat at Everton in September.

Cologne have given Song a �600,000 contract with an option for him to stay for three more years.

Lienen said he will be throwing the Cameroonian into immediate action this weekend against St Pauli in a Bundesliga game.

Brash tackles

The news is a massive boost for the Indomitable Lions, who will be defending their title at the African Nations Cup, starting on January 19.

He led Cameroon to victory at the 2000 Nations Cup and helped them qualify for next year's World Cup finals.

Known for his uncompromising style of play, Song set a record in 1994 when, at 17, he became the youngest player to be shown a red card at the World Cup.

But since then, he has grown in stature to become an influential part of the Cameroon national team.

He was in the Indomitable Lions' team that battled Poland to a 0-0 draw in a friendly earlier this month.

Song's nomadic career has included spells at French side Metz and Italian club Salernitana.