* Ujah has scored 10 goals this season
* 24-year-old is Nigeria international (Adds Werder announcing four-year deal))
BERLIN, May 5 (Reuters) - Striker Anthony Ujah, who scored 10 goals in the Bundesliga this season to virtually ensure Cologne's survival in the top flight, has signed a four-year contract with Werder Bremen.
The 24-year-old Nigeria international, who initially joined on loan in 2012 from Mainz 05 before making the move permanent a year later, asked for the transfer himself and passed a medical at Werder before signing his contract from next season.
"We looked into him for very long and very intensively to have a full picture," said Bremen sports director Thomas Eichin.