Vietnam has delayed the introduction of new boat safety rules at a top tourist site where 12 people drowned in February, after tour operators went on strike in protest, an official said Monday.

Almost 500 boats refused to operate last Friday on Ha Long Bay, one of the country’s most popular tourist attractions, because of new safety regulations which were to take effect that day.

"This decision essentially concerns safety equipment, and fire-fighting and prevention measures," said Luong Song Thuong, an official at the tourist port which serves the popular bay northeast of Hanoi.

"The managers of the tourism boats explained that they need time to respond to the new standards imposed by the local authorities."

The new safety measures — including a requirement that boats carry global positioning systems — will require considerable expenditure by the operators, Thuong added.

She said the boats resumed work on Saturday after the provincial government decided to delay implementing the new regulation until September 10.

In Vietnam’s worst tourism accident, 11 foreign tourists and their guide drowned in February when a boat sank at night on Ha Long Bay, a UNESCO World Heritage site known for its stunning limestone cliffs.

A senior provincial official said water leakage resulting from human error was the most likely cause of that incident.

The boat’s captain and engineer were arrested for investigation over alleged safety violations, which prompted authorities to vow a crackdown on the boats.

In an eerie echo of that tragedy, 28 French tourists had a lucky escape in May when their boat began sinking on Ha Long Bay. There were no injuries.