A wave of co-ordinated explosions have hit Thailand, leaving four dead and and more than 20 injured.

Two people were killed and more than 20 were wounded, many seriously, in the seaside resort of Hua Hin in two bomb attacks on Friday and two on Thursday.

Thursday's blast left one woman dead and at least 21 people - including several foreigners - were injured, while another death was reported in Friday's blast.

Two further bomb attacks were reported in the southern provinces of Trang and Surat Thani, with one death in each location. Six people were also injured in the Trang blast.

One person was wounded after two small explosions hit the popular tourist island of Phuket.

Thai police have said that they do not think the blasts were linked to terrorism, but believe they were local sabotage.

A police officer in Phuket reported that one bomb exploded near a police box, wounding one man, while the second blast was around 300 metres away and no one was injured.

It was not immediately clear who was behind the attacks.

The two bombs which exploded in Hua Hin on Thursday were hidden in potted plants and were set off within 30 minutes of each other in the bar district of the popular beach town, according to Gen Sithichai Srisopacharoenrath, the police superintendent in Hua Hin, and his deputy, Lt Gen Samer Yousamran.

Gen Sithichai said both devices were hidden inside plants on a busy street filled with restaurants, bars and food sellers that is popular with tourists and residents.

He said one Samsung mobile phone had been recovered that police believe was used to detonate at least one of the bombs.

The blasts come as Thais celebrate a long weekend for Queen Sirikit's birthday.

On Sunday Thai voters approved a referendum on a new constitution that is supposed to lead to an election next year. Critics say it is undemocratic and is fashioned to keep the military in control for at least five more years even if a free election is held.

In a speech on Wednesday night, junta chief and prime minister Prayuth Chan-ocha took credit for bringing stability back to Thailand after an extended period of unrest.

The string of blasts include: