SEVILLE: Spanish club Sevilla says the national anti-doping agency is looking into reports that midfielder Samir Nasri recently had intravenous treatment at a Los Angeles clinic.

The clinic, Drip Doctors, posted a photo of Nasri on its Facebook and Twitter accounts on Tuesday, saying it had provided him with a drip "to help keep him hydrated and in top health during his busy soccer season."

It describes the drip as an infusion to boost the immune system and contains "high dose vitamin C, B vitamins, lysine and zinc combined with specially formulated nutrients."

Sevilla spokesman Jesus Gomez told The Associated Press on Friday that "the agency has been in contact with the club to ask for information" about the player.

A spokesman for the anti-doping agency told the AP that its investigators are checking whether any treatment Nasri may have received had steered clear of the list of prohibited substances. The spokesman spoke anonymously as dictated by agency policy.

The 29-year-old Nasri, who is on loan from English Premier League club Manchester City after not fitting into new coach Pep Guardiola's plans, returned with the rest of his teammates from their winter break to start training on Friday.

Nasri has proved to be a key player for Jorge Sampaoli's Sevilla, which has reached the Champions League's round-of-16 and sits third in the Spanish league at the winter break.