Indian Olympic bronze-medallist boxer Vijender Singh has been questioned over his alleged links to a $24-million heroin haul and has refused to give blood or hair samples, police said Tuesday.

Singh, who won a bronze at the 2008 Beijing Olympics, was interviewed near Chandigarh in northwest India on Monday evening after an alleged drug dealer arrested with the heroin named him and fellow boxer Ram Singh as "clients."

Vijender, 27, who became a household name in India after winning the Olympic medal, has strongly denied any link to the drug dealer and slammed as "ridiculous" the allegations against him.

Police seized 26 kilograms (57 pounds) of heroin worth 1.3 billion rupees ($24 million) last week in the northern state of Punjab. The alleged dealer was arrested along with five others.

Vijender, himself a police officer in the neighbouring state of Haryana, was questioned for close to four hours on Monday evening, according to a police statement reported by the Press Trust of India (PTI).

"The Punjab Police tied up with Haryana Police for questioning of Vijender Singh," the statement said. "The team questioned him regarding the drug case registered last week.

"As per procedure, he was asked for his consent for giving his blood and hair samples required for forensic examination for investigation purposes, which he refused."

Punjab Police official H.S. Mann, who is probing the case, told AFP by phone that investigations were ongoing. "Its a very serious matter," Mann said without elaborating.

The Indian sports ministry said it was closely watching the investigations and the boxer will face action if he is found guilty of any wrongdoing.

Ram Singh, who confessed to reporters that both he and Vijender had "experimented with drugs thinking they were food supplements," has already been thrown out of a training camp for boxers in Patiala.

There have been a number of major drug seizures in Punjab in recent years. A Punjab university study in 2011 suggested that up to 70 percent of the state's youth were addicted to drugs or alcohol.