ATHENS (Reuters) - The crew members of a yacht accused of starting a forest fire last week on the Greek island of Hydra denied arson charges on Wednesday when they appeared before a judge, a legal source and local media said.

Wildfires are common in the Mediterranean country but they have become more frequent and devastating due to hotter, drier and windier weather, which scientists link to climate change. Greece has in recent years beefed up penalties for arson.

The fire, which is believed to have been sparked by fireworks, broke out on Friday night, devouring nearly 300,000 square metres of the island's only pine forest before fire fighters tamed the flames early on Saturday.

The 13 Greek crew members of the yacht, which had been moored 350 metres (383 yards) from the shore when the fire erupted, were arrested on Sunday at a marina near Athens and charged with starting the blaze.

They have all denied any wrongdoing and they reiterated their stance before an investigating magistrate at the court of Piraeus on Wednesday.

In a statement cited by the Athens News Agency, the company operating the yacht, Salaminia Yachting LTD, said it awaits the results of the investigation and that it "retains absolute confidence in the integrity and sincerity of the crew members", who have stated that they were not involved in the incident.

The legal source said earlier that there was not enough evidence to link them with the case and that the captain of the vessel had been the first person to alert authorities about the fire, while other yachts were also in the wider area.

Witnesses testified that they saw smoke and flames after hearing 15 to 20 loud sounds, similar to firework explosions, at 10:30 pm (1930 GMT) on Friday night, according to court documents seen by Reuters.

One of them said they had seen a rubber boat sailing towards the yacht as the fire was spreading fast. They later saw a fire extinguisher on the yacht's stern. 

(Reporting by Renee Maltezou; Additional reporting Yannis Souliotis; Editing by Gareth Jones and Bill Berkrot)