Visitors to Thailand are being warned to be cautious and avoid public places after a series of bomb attacks in which four people died.

Government offices, police stations and popular tourist spots in the south of the country were all targeted.

Dozens of people were wounded in the blasts on Thursday and Friday, including 11 foreigners.

No-one has claimed responsibility for the attacks, which followed a referendum held last weekend on a new constitution.

However, they appeared to be aimed at damaging the tourism industry, which provides vital income for the government.


Image: Popular tourist destinations have been targeted in the attacks

One small bomb exploded on a beach in Patong on the island of Phuket and four others went off in the seaside resort of Hua Hin, emptying the streets.

Police said firebombs also triggered blazes at markets and shops in six other places, including Trang and Surat Thani.

Thailand's economy has slumped since the military coup in 2014, but tourism has remained one of the few bright spots with visitor numbers increasing.

Following the blasts, the British embassy updated its travel advice and warned holidaymakers to "exercise extreme caution".

Image: More than 30 people have been injured in the blasts, which left four dead Image: Some of the bombs are reported to have been concealed in plant pots Image: Some of the devices are thought to have been detonated remotely using mobile phones Image: Investigators have blamed 'local sabotage' for the attacks Image: The British embassy has warned holidaymakers in Thailand to be 'cautious' Image: An injured man is rushed for treatment Image: Thailand has been plagued by political violence for much of the past decade Image: The wave of attacks comes less than a week after Thais voted to adopt a military-backed constitution Image: The explosions will be a blow to tourism, a major source of income to the country /

In a televised address on Friday, Prime Minister Prayuth Chan-ocha said the attacks "struck at the hearts of all Thai people."

He said it was unclear who carried them out but the government would do its best to find out.

Police said earlier they were investigating all leads, but had ruled out links to international militant groups.

The violence began on Thursday afternoon when a bomb exploded in the province of Trang, killing one person and injuring six, according to police.

On Thursday night, attackers in Hua Hin set off bombs in a busy street filled with bars and restaurants.

Thailand Bombings Timeline

They were hidden inside two potted plants and detonated by mobile phones about half an hour apart

One Thai woman was killed and about 20 people were wounded, 11 of them tourists.

Police said four were from Germany, two from Italy and one from Austria. The Netherlands said four of its citizens were also wounded.

Hua Hin was hit by another two bombs in quick succession on Friday morning near a clock tower, killing one person and wounding four more.

Separate blasts were reported elsewhere in the south on Friday morning.

One bomb exploded on Loma Beach in Phuket city's Patong district, injuring one person.

Two others went off half an hour apart in front of two police stations in Surat Thani, killing one person and wounding three.

Two blasts outside a market in Phang Nga damaged two vehicles but no-one was hurt.