By Mike Collett

LONDON (Reuters) - West Ham United confirmed on Thursday they had signed Argentines Carlos Tevez and Javier Mascherano from Brazilian club Corinthians on permanent deals.

The club said on its official Web site that "the pair have been signed for an undisclosed fee and put pen to paper on permanent contracts with the club this afternoon.

"All other aspects of the transfers will remain confidential and undisclosed."

The deals represent a big coup for the Hammers, who have beaten off some of Europe's biggest clubs including Arsenal and Manchester United to sign the pair. Both played a key roles for Argentina at the World Cup where they reached the quarter-finals.

The transfers echo the shock double signing of Ossie Ardiles and Ricardo Villa who joined Tottenham Hotspur just weeks after Argentina won the World Cup in 1978.

That deal transformed Tottenham's fortunes in the late 1970s and early 1980s and Tevez and Mascherano will become heroes in east London if they are anywhere near as successful as Ardiles and Villa were at Spurs.

Tevez, 22, is one of the most talented young strikers in the world. Widely described as 'the new Diego Maradona', he is one of the few players who might live up to that tag.

He began his career with Maradona's old club Boca Juniors, making his debut at the age of 17 and helped Boca to the Argentine championship and the Copa Libertadores.

In December 2004 he moved to Corinthians in a $22.6million deal, the biggest ever in South American football.

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Initially he struggled in Brazil but soon won the supporters over and became captain with the club securing the Brazilian championship in 2005.

He has played 25 times for Argentina, scoring four goals.

Mascherano, also 22, is a highly rated defensive midfielder who adds a touch of granite to Argentina's attacking play.

Mascherano left Argentine club River Plate, the great rivals of Boca Juniors, to join Corinthians in 2004, for $15million, and helped them in their title success last year.

With 20 caps for the national team, he is considered one of the county's hottest properties and has also been linked with a number of top European clubs recently.

Both players are in London preparing for Argentina's friendly against Brazil at Arsenal's Emirates Stadium on Sunday and should make their debuts for the Hammers against Aston Villa next week.

West Ham also announced they had signed Marek Stech, the Czech Republic's Under-17 international goalkeeper from Sparta Prague.

The Tevez-Mascherano deal is not the first time West Ham and Corinthians have been linked.

Just over a year ago an investment group, Media Sport Investment, which bought Corinthians in 2004, were in negotiations to buy West Ham.

MSI, headed by Iranian-born businessman Kia Joorabchian, had talks with the West Ham board in August 2005.

Joorabchian had said that he would spend 200 million pounds ($381.4 million) in total, half of it on new talent, but the deal failed to go through.