"I'm pleased to have Radoslav here," added Zola. "He has a lot of experience with the national team and I'm sure he will help us with what we are trying to achieve this season."
Kovac admitted that manager Gianfranco Zola's presence at West Ham played a big part in persuading him to join the club.
"There was interest from other big clubs but when West Ham showed their interest, it felt like the right move for me and a chance to come and play in the Premier League," he told the club's official website, www.whufc.co.uk.
"Of course I know a lot about the manager and also the player he was. He says it is a fantastic opportunity for me to come and play under him and I am very excited about this.
Earlier in the week West Ham beat off "fierce competition" from Europe's leading clubs to complete the signing of 19-year-old Brescia striker Savio Nsereko.
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