China has said five suicide bombers who killed 31 people in the autonomous Xinjiang region were probably influenced by terrorist groups outside the country.

Foreign Ministry spokesman Hong Lei said the bombers had been radicalised by extremist Internet sites.

Thursday’s attack is the deadliest in the troubled region to date and the second suicide bombing in the region’s capital Urumqi in just over three weeks.

The attackers drove two vehicles into a market and threw explosives out of their windows.

Many of the nearly 100 wounded were elderly shoppers, according to witnesses.

China’s minister of public security went to the site of the attack and later visited injured victims in hospital.

China has blamed a series of recent attacks on separatist militants.

Many rights groups blame the unrest on government policies, including curbs on the culture and language of Uighurs, a Turkic ethnic minority people that have long complained about official discrimination in favour of the majority Chinese ethnic Han population.

Residents said the market where the attack occured was frequented by Han customers, though many of the vendors were Uighers.

Nobody has claimed responsibility for the Urumqi attack.