Media playback is unsupported on your device Media caption The two men were captured on CCTV standing near the main suspect, in yellow

Two men identified as suspects in the Bangkok bombing have been cleared of involvement, police say.

The pair were filmed by security cameras standing near the prime suspect in Monday's blast at the Erawan Shrine, which killed 20 people.

A police spokesman said they were now satisfied the men - a Chinese tourist and his Thai guide - were not involved.

The main suspect remains at large, but authorities told the BBC they believe he is still in Thailand.

Dozens of people were injured in the explosion, with some losing limbs.

Police had said that at least 10 people were suspected of involvement in the attack, and that their prime target was foreign.

CCTV shows main suspect's movements before and after blast

What we know so far?

Image copyright EPA Image caption The remains of some of the victims have been released to their families

Media playback is unsupported on your device Media caption Locals will never forget the bombing, but life goes on at the shrine

Media playback is unsupported on your device Media caption The BBC's Jonathan Head found shrapnel at the site of the blast

The two former suspects, wearing red and white t-shirts, were captured standing in front of the main suspect, in yellow, as he left his backpack under a bench at the scene.

The footage led police to believe the pair may have been the attacker's accomplices.

But one of the men "met police and was released", according to police spokesman Prawut Thavornsiri.

He told them he had taken the Chinese man to the Erawan shrine on behalf of a mutual friend.

Earlier reports suggested both of the men had presented themselves for questioning.

But the Chinese national returned home a day after the bomb, Mr Thavornsiri said.

Neither were "likely involved", he added.

Image copyright Thai police Image caption Thai police released this sketch of the "man in yellow", suspected of planting the bomb

Image copyright AP Image caption Images released by Thai police show him in a tuk-tuk near the shrine before the bombing...

Image copyright AP Image caption ... and riding away from the scene afterwards on the back of a motorcycle taxi

Earlier on Thursday, Col Winthai Suvaree, a spokesman for the ruling military junta, said the preliminary conclusion was that it was "unlikely" the attack was the work of an international terror group.

However, he later told Associated Press that a global terrorism link had not been ruled out, saying: "We still have to investigate in more detail."

Suspect's CCTV trail: Jonathan Head, BBC News, Bangkok

Image copyright AFP

Images of the main suspect before and after the bombing give a chilling picture of a man on a deadly mission.

We see him getting out of a tuk-tuk 18 minutes before the blast, with a black backpack. He is no more than three minutes walk from the shrine, and starts towards it.

He appears again at 18.49.30, about 100m on from the previous CCTV camera. We then see him walking into the shrine, taking off the backpack, and putting it on the ground, under the bench he is sitting on.

He walks out. It is less than three minutes before the explosion.

The cameras then pick him up walking back along Rajdamri Road, past the Hyatt Hotel, looking at his phone.

The next camera catches him at 18.56.06, 48 seconds after the blast, walking fast.

We see him next on the back of a motorbike taxi, heading south, towards Lumpini Park, where the driver has told police he dropped him off. The police say they have lost all trace of him since then.

Bangkok bomb: CCTV timeline

Police are also questioning a tuk-tuk taxi driver who drove the main suspect to the shrine, but are making slow progress in identifying the name and nationality of the man in yellow.

Although the shrine has been cleaned up, a BBC team led by Jonathan Head was still able to find bomb shrapnel embedded in a wall nearby, suggesting the forensic teams have not yet collected all possible evidence from the area.

No-one has yet said they carried out the attack.

National police chief Somyot Pumpanmuang said he believed the attack was planned at least a month in advance.

Prime Minister Prayuth Chan-ocha has called the bombing the "worst ever attack" on Thailand.

Twelve of the 20 dead in Monday's attack were foreigners, including nationals from China, Hong Kong, the UK, Indonesia, Malaysia and Singapore.

Bangkok explosion