A severe shortage of dentists on Lewis is forcing islanders to seek treatment on the mainland.

Waiting lists have been frozen on the island and unregistered patients can only receive treatment in emergencies.

The equivalent of six full-time dentists work in Stornoway and the town's £4.7m dental centre, which opened in 2011 and boasts seven purpose-built surgeries, is underused.

Islander Margaret Murray has launched a petition urging the Scottish Government to intervene.

"The only way we can register as NHS dental patients at the moment is to travel away from the island, to a town such as Inverness," she said.

"Such a journey not only requires considerable expense but depending on a person's employment and family circumstances would also usually necessitate an overnight stay on the mainland.

"Many residents simply cannot afford the expense and inconvenience of travelling to Inverness every few months for dental treatment."

Each of the island's dentist is responsible for between 2000 and 2500 people, which cannot be increased for "safety reasons," according to NHS Western Isles.

A spokeswoman said: "We do currently register special needs groups and emergency dental care continues to be available for anyone assessed as requiring that."

She added: "Proposals have been developed to redesign the service but unfortunately have not yet been agreed."

Lewis and Harris have one dentist for every 3138 people, while the Uists and Benbecula have one for every 1615 people. On Barra, one dentist covers 1160 people.

A Scottish Government spokesman said NHS Western Isles is making "continuous efforts" to improve local dental services.

He added: "We are committed to ensuring that patients who wish to have access to NHS dental services are able to do so.

"Across Scotland, more than 4.9 million people have now registered for NHS dental services, and the total number of independent dental practitioners providing NHS services have risen by more than 30% under this government."