Security tightened at Champions League games after IS threats

France and Spain will step up security ahead of the Champions League quarter-finals being held in Madrid and in Paris on Tuesday and Wednesday nights, top government officials said, citing threats from IS.

"Regarding the game that will take place in the Paris region, the head of police has considerably strengthened security," French Interior Minister Gerald Darmanin told reporters at a press event on Olympic Games security.

Paris-St-Germain are due to play Barcelona in Paris on Wednesday night.

"We have seen, among other things, a communication...that particularly targets stadiums. It is not new," he added.

IS was alleged to have threatened four venues for this week's Champions League matches, including the Parc des Princes in Paris and two games in Madrid hosted by Real Madrid and Atletico Madrid, who face Manchester City and Borussia Dortmund respectively.

In London, Arsenal take on Bayern Munich in their quarter-final on Tuesday night. British police will have a "robust policing plan" in place, a police statement said.

Spanish police forces will deploy 2,000 extra officers to boost security in the capital for the two games, government spokesperson Pilar Alegria told reporters on Tuesday.

She said the terrorism alert level had been raised to 4 on a scale of 5.

IS has claimed responsibility for the recent attack on a Moscow concert hall that killed at least 143 people.