Spain and France ramped up their security plans ahead of the Champions League quarter-finals matches this week due to a potential threat of terrorism.
"To prevent any terrorist threat, the state security forces have activated all of their early warning and protection systems as well as their defence mechanisms," the Spanish Ministry of the Interior said on Tuesday.
European football ruling body UEFA, meanwhile, said it is "aware of the alleged threats" and that the games will take place as planner, the PA news agency reported.
"UEFA is aware of alleged terrorist threats made towards this week’s UEFA Champions League matches and is closely liaising with the authorities at the respective venues," the statement said.
"All matches are planned to go ahead as scheduled with appropriate security arrangements in place."
On Tuesday, Real Madrid host Manchester City, while Atletico Madrid welcome Borussia Dortmund on Wednesday, when Paris Saint-Germain host Barcelona in France.
The Spanish Ministry of the Interior didn't explicitly mention possible terrorism threats from Islamist groups, but the Spanish media spoke of possible threats from jihadists.
The federal and state security forces have taken all necessary measures to ensure the safety of participants and visitors in the two games as well as Spanish citizens in general, the ministry further emphasized.
Some 2,000 police officers and other security personnel are to ensure that the two games go ahead safely.
French Minister of the Interior Gérald Darmanin said on Tuesday that security measures in Paris would be "considerably tightened" for Wednesday's games, the AFP news agency reported.
The highest terrorism threat level is already in force in France due to the 2024 Olympics this summer.