The golden sands and turquoise seas of the Maldives are a favourite location for couples looking to affirm their love in a location more exotic than the local register office.

But an important lesson can be gleaned from one unfortunate pair who renewed their vows on a Maldivian beach: make sure you know exactly what you're saying "I do" to.

The Maldivian foreign minister issued a grovelling public apology today to a Swiss couple who thought they were being blessed at an idyllic beach ceremony but were in fact being referred to as "swine" and "infidels" in the local tongue.

Police are investigating after a staff member at the Vilu Reef resort substituted marriage renewal vows with a stream of extreme sexual and religious slurs in the local Dhivehi language.

The public relations disaster unfolded after someone uploaded a video of the ceremony on YouTube, threatening the Muslim-majority country's reputation as one of the world's most exclusive tourist destinations.

"You are swine," the unwitting couple were told. "The children that you bear from this marriage will all be bastard swine. Your marriage is not a valid one. You are not the kind of people who can have a valid marriage. One of you is an infidel. The other, too, is an infidel and, we have reason to believe, an atheist, who does not even believe in an infidel religion."

After the video went viral, the Maldives government went into crisis management overdrive to protect its lucrative tourism industry.

"The Maldives is a world-class tourist destination famed for its warm welcome and excellent customer service. Episodes such as that captured on video have no place in our tourism industry or in our society more broadly, and are alien to our cultural and religious values," said the foreign minister, Ahmed Shaheed.

He said he had instructed the Maldives diplomatic service to apologise to the Swiss couple face-to-face and offer them compensation. Those "guilty of wrongdoing" will be "brought to justice", he vowed, adding that he would be seeking assurances from the Maldives tourism industry that the incident was a one-off.

"If we do not receive such reassurance, we reserve the right to take all remedial steps necessary, legislative or otherwise, to ensure that episodes such as that which occurred in Vilu Reef resort never happen again and do not tarnish the positive image of the country built up over so many years," he said.

Punishments can be brutal in the island nation. Last year Amnesty International claimed that at least 180 people faced being flogged in the Maldives as a penalty for extramarital sex.