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One of the sons of Philippine President Rodrigo Duterte has denied involvement in a drug smuggling operation.

Paolo Duterte told a senate inquiry that claims he helped ship drugs from China to the Philippines were "baseless".

The president's son-in-law also denied involvement, calling the allegations "rumours and gossip".

President Duterte launched a violent campaign against drug crime shortly after he came to power last year.

Mr Duterte, whose crackdown has left thousands of people dead, has promised to resign if any family members are involved in the trade.

Paolo Duterte and Manases Carpio, who is married to Mr Duterte's daughter, Sara, are facing allegations that they helped facilitate a shipment of crystal methamphetamine worth $125.4m (£96m) into the country from China.

The claims centre around the testimony of a customs broker who says he heard their names mentioned in connection with the consignment. He has since issued a statement saying they were not involved.

An opposition senator who is a staunch critic of the government told the panel that Paolo Duterte had a tattoo on his back that proved he was a member of a drug gang.

Media playback is unsupported on your device Media caption Duterte drug war: Manila's brutal nightshift

Paolo Duterte, who is the vice-mayor of Davao city, said he could not "answer allegations based on hearsay" and declined to describe his tattoo.

Mr Carpio said he had "no knowledge of, or involvement, in the illegal drugs shipment".

Mr Duterte, who became president of the Philippines in June 2016, is popular at home for his brutal and highly controversial crackdown on drugs.

Police figures say 3,800 suspects have been killed in anti-drugs operations since he took office. Several thousand more unexplained killings have been attributed to the crackdown. Rights groups have voiced serious concerns over extrajudicial killings.

Last month Senator Leila De Lima, a leading government critic detained on drugs charges she says are politically motivated, accused Mr Duterte of hypocrisy over his son, saying he was happy to target poor drug users but "his silence on the tonnes of illegal drugs that slipped past customs is deafening".

A presidential spokesman said the pair's attendance at the senate inquiry showed they were "ready to face malicious allegations intended to impugn their character".