Wellington, Sep 7 (IANS): The New Zealand government on Monday admitted that more foreign sailors without work visas have been allowed to operate in the country's waters.

In July, Radio New Zealand revealed seafarers aboard a Philippine ship were earlier this year allowed to work at Port Taranaki without the correct paperwork.

The Merchant Service Guild, which represents workers in seagoing ships, said the problem was getting worse.

It said workers on the US-flagged "Roger Revelle", which has just wrapped up oceanographic research off the North Island's east coast, did not have work visas. The guild also said visas for sailors on the Dutch dredger "Brage R", which has been in the country for several weeks, were only granted at the end of last week.

Master mariner Kevin Judkins, who has more than 35 years of experience in the oil and gas industry, said things were getting slack.

"It's something that's become more predominant over the past couple of years," he said.

According to Immigration New Zealand, the crew of any foreign ship operating off the country's coastline must have work visas.