By south-east Asia correspondent Karen Percy & wires

At least one Australian has been injured in a series of bomb attacks that killed at least four people and hurt 72 others in southern Thailand.

Two of the bombs were left on motorbikes parked in Hat Yai's busy entertainment and shopping district, where it is believed they were set off by mobile phone.

The other four were planted near the entrances of two department stores and a hotel frequented by foreigners.

Authorities say a 29-year-old Canadian teacher is among the latest dead.

They say 14 other foreigners are among the 72 wounded, including six Malaysians, three Singaporeans, three Britons, an Indian and an American.

Outside the Brown Sugar Bar and Cafe, a distraught Australian visitor, still wearing his hospital gown, has stood staring at the wreckage of where he was drinking the night before.

"I feel really lucky today," he said.

Doctors have removed shrapnel from the shoulder of the man, who has not given his name.

His girlfriend has suffered multiple fractures to her leg.

Thai TV has shown bloodied victims lying in restaurants or being led to safety by rescue personnel, as vehicles burned in streets strewn with shattered glass and overturned tables and chairs.

The explosions prompted authorities at one stage to switch off the mobile phone networks in the area to prevent further attacks.

Separatist insurgents are being blamed for the blasts.

While Thailand's security agencies have been anticipating violence in the south in recent days, they were not expecting an attack in the city of Hat Yai, which borders the southern provinces.

It is the second coordinated bombing attack in the region since the end of August.

Thailand's Government is under pressure to find a solution in the three Muslim-dominated provinces because emergency powers enacted more than two-and-a-half years ago have failed to quell the violence.

- AFP/ABC