West Ham United are delighted to announce the permanent signing of Mexico striker Guillermo Franco after the expiry of his contract with Villarreal CF.

The Argentinian-born forward arrives fresh from his goalscoring exploits with his adopted country. He has scored four goals in his last six internationals since June, including one in the 3-0 win away to Costa Rica in 2010 FIFA World Cup qualifying last week.

He had been linked with a move to South American champions Estudiantes as well as two Spanish clubs, with CEO Scott Duxbury and technical director Gianluca Nani securing his services after positive negotiations over the last fortnight. Franco was set to link up with his new team-mates for the first time on Thursday but it is not yet certain if he will be involved against Liverpool this weekend.

Franco, who has put pen to paper at the Boleyn Ground and passed a medical, said: "I am really happy to sign for West Ham. It was my dream to come to the Premier League and I am proud to play for a club that has so much history. This is a very important stage in my career and I hope to score lots of goals for the club this season and then play at the World Cup.

"This is an important team with great players and a great manager. I know that the club are very ambitious and want to do well. I want to do my best to make that happen and I am excited about the challenge.

"The main motivation was to play in the Premier League. I love English football and I love the Premier League. I had the possibility of joining Estudiantes and two Spanish clubs, but it was the Premier League that drew me here. I can fulfil my desire with West Ham and I am very happy to be here."

Franco's arrival means an array of attacking options in the final third for Zola. He has in his squad England internationals Carlton Cole, Kieron Dyer and the injured Dean Ashton, new Serie A recruits Alessandro Diamanti and Luis Jimenez plus the exciting trio of Junior Stanislas, Frank Nouble and Zavon Hines.

Duxbury said: "I am very pleased to be able to welcome Guillermo to West Ham as I was determined to deliver the extra attacking options that Gianfranco wanted for the new season. Alessandro Diamanti has settled in very well already to what is a strong squad and it is clear how keen Guillermo was to come as well. He understands what we are trying to achieve and his high level European and international experience will be invaluable."

After starting with San Lorenzo in Argentina, Franco shot to attention with Mexican side CF Monterey, scoring 63 goals in 119 league appearances including a league title in his first campaign and two runners-up medals after that. He earned a high-profile move to Villarreal in January 2006 and, after appearing at the World Cup finals later that summer, helped them qualify for the Champions League with eight goals in the 2007/08 season from 16 starts and eight substitute appearances.

The 32-year-old played six times in Europe's premier club competition last season, including the 1-1 home draw with Arsenal in the quarter-finals on 7 April. He also has experience of playing at the Boleyn Ground, having figured for 67 minutes in the inaugural Bobby Moore Cup against West Ham United a year ago, with the match finishing in a 1-1 draw.

Franco added: "I played here before with Villarreal and I have also played Champions League games here in England. I thought then that I would like to play here one day and maybe that match against West Ham meant that it was destiny that I would come here to play."

The striker, who also scored in the final as Mexico won their continental Gold Cup in June with a 5-0 defeat of the United States, will be the first Mexican international to play for West Ham.