Image copyright Family photos Image caption Hannah Witheridge and David Miller were killed in an attack on the island of Koh Tao last month.

A plea to postpone the start of the pre-trial hearings of two Burmese men charged with the murder of two UK tourists in Thailand has been rejected.

Defence lawyers wanted a delay to allow more time to prepare.

The men apparently confessed to the killings earlier this month. Police have denied subsequent reports the pair then withdrew their confessions.

Hannah Witheridge, 23, and 24-year-old David Miller were killed in an attack on the island of Koh Tao last month.

Post-mortem examinations found Mr Miller, from Jersey, died from drowning and a blow to the head, while Miss Witheridge, from Great Yarmouth, died from head wounds.

The police investigation into the murders has been widely criticised. On Monday the UK Foreign Office summoned the Thai charge d'affaires to express concern.

The two suspects were in court for a pre-trial witness hearing on the island of Koh Samui on Tuesday, but did not testify.

Three potential witnesses, also of Burmese origin, are due to take the stand.

The two suspects, both aged 21, are charged with conspiracy to murder, conspiracy to rape and robbery.

Lawyers representing the pair have argued for the proceedings to be postponed because they say they have been allowed too little time to prepare a defence.

Thai police have been criticised for allegedly not allowing lawyers or translators to be present when the suspects were questioned.

Image copyright Reuters Image caption Koh Tao is a popular destination for tourists

Foreign Office minister Hugo Swire summoned Nadhavathna Krishnamra, the Thai charge d'affaires to the UK, on Monday to express concern over the way the investigation has been handled since the bodies were discovered on a beach on 15 September.

The Foreign and Commonwealth Office said it followed a call made by Mr Swire to Thailand's deputy prime minister and foreign minister earlier this month.

The Burmese government and parliament have also issued statements of concern.

But, as the pre-trial hearing began on Tuesday, Thai Prime Minister Prayuth Chan-ocha dismissed growing concern and denied that the Thai charge d'affaires had been summoned.

He said: "They did not summon us. We went to provide clarification to them.

"We went to show them how we work. They might be surprised at how quickly we work but we explained the steps we have in place."

'Fair and transparent'

In a statement, the Foreign Office said: "Mr Swire stressed that there was a real concern in the UK about how the investigation has been handled by the Thai authorities.

"He said that it was crucial for the investigation to be conducted in a fair and transparent way."

British ambassador Mark Kent tweeted that he had a nearly three-hour meeting with the Thai police and Ministry of Foreign Affairs, and the Burmese ambassador and delegation, about the murders.

Thai police say that DNA found on Ms Witheridge matched samples taken from the men.

Funeral services for Mr Miller and Ms Witheridge have taken place in recent weeks.

Koh Tao