At least one of three security guards at an Antigua hotel where a British couple were shot dead on their honeymoon may have been asleep at the time, according to testimony in the trial of two men charged in the killing.

Security guard Ian Newell's account of the night is vague. He told jurors he was sleeping during his shift at the Cocos Hotel and that he never heard shots.

He said he only realised there was trouble when a guest came to him for help. But he did not specifically say he slept through the murders of Welsh couple Catherine and Benjamin Mullany in July 2008.

"Sometimes you work, you feel drowsy you take a nap," Newell told the jury, adding that he would get sacked if caught sleeping on the job.

At some point, he recalled only the commotion that followed the shooting. The guests came and were shouting at him. He went and saw what happened in their cottage overlooking the ocean and ran for help.

Another guard stationed at the entrance to the hotel previously testified that the property's gate had no lock and that he learned of the killings from Newell.

The Mullanys were attacked during an apparent robbery at their holiday cottage on the last day of their two-week honeymoon. Both were 31 and from Wales.

The suspects, Avie Howell and Kaniel Martin, have pleaded not guilty. They are accused of shooting a Jamaican shopkeeper, Waneta Anderson Walker, during an alleged crime spree in July 2008.

They are expected to face a later trial in two other deaths on the Caribbean island.