By Richard Martin
MADRID (Reuters) - Spanish authorities are expecting between 400 and 500 potentially violent fans for Sunday's Copa Libertadores final between River Plate and Boca Juniors which was moved to Madrid after trouble in Argentina.gi
Four thousand security personnel, between police and private forces, will be on duty watching for troublemakers at Sunday's game between the Argentine arch-rivals at Real Madrid's Santiago Bernabeu stadium.
After a 2-2 draw in the first leg of the South American club final, the return game was originally scheduled for Nov. 24 at River's Monumental stadium in Buenos Aires.
But it was postponed twice then moved 10,000 kilometres (6,000 miles) to the Spanish capital after fans ambushed Boca's team bus on arrival, injuring several players.
"Police are working closely with Argentine forces. There are a group of between 400 and 500 people who are especially violent," local government delegate Jose Manuel Rodriguez Uribes told a news conference on Friday.
"We are working on establishing maximum security at the airport, the roads, bus stations and metro stations to detect violent people and those who have criminal records."
One well-known Boca Juniors hooligan was deported from Madrid's international airport on Wednesday, though the leader of the team's most hard core gang has been cleared to travel.
The clubs have been given 25,000 tickets each: 20,000 for fans in Europe and 5,000 for supporters crossing the Atlantic for the 'Superclasico' between Argentina's biggest clubs.
Argentina's largest diaspora is in Spain, 250,000 people.
Boca forward Carlos Tevez said Spain was right to apply a zero tolerance policy to violence though he believed this game would go ahead without major incident.
"It's important Spain are making an example of the 'barra bravas' (gangs) and are cracking down," he told reporters at Boca's base at the Spanish national team's headquarters.
"I think people are smart, they know they can't cause trouble here and everything should happen peacefully. It's important for everyone involved to know that while it is a final, of course, it is a football match."
Police will seek to keep rival fans apart and will close Paseo de la Castellana, a main road from the city centre to the stadium, Madrid official Rodriguez said.
"We hope this is a day of celebration," he said.
(Reporting by Richard Martin; Editing by Andrew Cawthorne)