The Mercedes team has been ordered to face an investigation by the International Tribunal of motor racing's ruling body, the International Motoring Federation (FIA), into allegations that they conducted illegal in-season testing with Pirelli tyres.

The tribunal has wide-ranging powers if it finds Mercedes broke the FIA rules and can impose penalties ranging from fines to exclusion from the world championship.

The announcement that the German team will face further investigations, following a report by the stewards at the Monaco Grand Prix, came late on Wednesday evening.

Mercedes had been investigated by the stewards following protests lodged by Ferrari and Red Bull, both teams claiming that Mercedes took part in testing with Pirelli following the Spanish Grand Prix last month.

In a statement, the FIA said: "In the light of all the replies received and in view of the information gathered during this inquiry, the president of the FIA, acting as the FIA prosecuting body, has decided:

"To close the case as regard to Scuderia Ferrari Team considering that its participation in a tyre test organised by Pirelli in Barcelona on 23-24 April 2013 using for this purpose a 2011 car is not deemed to contravene the applicable FIA rules.

"To bring the case concerning the tyre testing session carried out by Pirelli and Team Mercedes AMG Petronas F1 in Barcelona on 15-17 May 2013 before the FIA International Tribunal because it results from the inquiry that the conditions of this testing may constitute a breach of the applicable FIA rules.

"The FIA International Tribunal is called upon to make a decision in compliance with the FIA Judicial and Disciplinary Rules."

The sport's governing body explained that it requested information from those involved and rival teams before coming to its conclusion.

It was ironic that Ferrari's own test with Pirelli, conducted at Barcelona in April with a 2011 car, was deemed not to breach the rules as they were one of the two teams leading the protests against Mercedes.

The announcement is not expected to have any effect on the team's preparations for this weekend's Canadian Grand Prix in Montreal.