Singapore police said on Thursday they were investigating a Spanish couple for protesting billionaire Peter Lim's ownership of LaLiga side Valencia and had impounded their passports.

Lim, 71, became the new majority owner of then debt-ridden Valencia in 2014 via his Hong Kong-based investment company Meriton Holdings. His ownership of the club has become deeply unpopular among the fan base who are unhappy with the selling of star players and a revolving door of managers.

Valencia are struggling in La Liga and are in the relegation zone, third from bottom of the table with just six points from their opening nine matches.

Police said a 34-year-old man and a 30-year-old woman were helping in the investigation after the couple was found to have taken part in a "public assembly."

In Singapore, public assemblies include staging protests or publicising a cause and require an official permit.

The police did not name the couple but several media outlets including the BBC identified them as newlyweds Dani Cuesta and Mireia Sáez on their honeymoon in the city state.

Last week Cuesta posted on his X account photos of him holding a black and yellow banner that reads "Lim go home" at various locations in Singapore, including outside the billionaire's home. He also pasted a sticker saying "Lim out" on the gate of the businessman's compound.

The "Lim go home" banner is a common sight during regular fan protests in Spain. However, protests are frowned upon in tightly-regulated Singapore and those who take part without a permit can be fined up to $3,000.

The couple's family issued a statement asking the media to show discretion, saying the priority was to get them swiftly released and returned home.

Spain said its embassy in Singapore was providing assistance to those affected. Valencia said it hoped the issue could be resolved quickly.