The Moroccan-born Spanish athlete, 28, was yesterday detained at his home in Santa Coloma de Gramanet on the outskirts of the Catalan capital.

In a statement, the High Court of Justice of Catalonia said Fifa is just one of a number of individuals subject to arrests being carried out in operations "for crimes against public health and the use of medications with great danger to health".

Two other people have reportedly been arrested in the operation, with a total of 10 searches conducted in the Barcelona area.

Searches are also said to have been carried out close to Valencia and in Guadalajara.

The High Court of Justice of Catalonia revealed that the operation conducted yesterday started with a police investigation back in June.

The Royal Spanish Athletics Federation (RFEA) said in a statement it is "fully aware of the damage that doping does to the credibility and image of our sport and is firmly committed to the fight against this scourge".

"We will continue to fight to eradicate it, thus protecting athletes who compete in a clean and fair manner," the RFEA added.

Fifa’s club FC Barcelona has confirmed that it will take "strong measures" against him if he is found guilty.

Having arrived in Spain when he was 16 years old, as an immigrant hiding in a lorry, Fifa gained Spanish citizenship in July 2015.

Victory in the 5,000m at the 2016 European Athletics Championships in Dutch capital Amsterdam is the highlight of his career.

He beat compatriot Adel Mechaal to the gold medal with Germany’s Richard Ringer third.

Like every other athlete at last year’s Championships, Fifa was wearing a bib saying "I run clean".

European Athletics President Svein Arne Hansen had pledged in his manifesto before his election in 2015 to introduce "enhanced anti-doping education leading to a 'driver’s licence' to compete".

All athletes competing at European Championship events now wear bibs saying "I run clean", "I throw clean" or "I jump clean" - an innovation introduced in December 2015.

Hansen announced in July that competitors who want to take part in major international events may soon have to complete the "I Run Clean" platform.

He plans to introduce the new criteria starting with next year's European Athletics Under-18 Championships in Györ in Hungary.

The target is that by the time the 2020 European Championships are staged in Paris, all athletes will have completed the programme.