BANGKOK (AFP) - Thailand suffered a plunge in tourist arrivals in May as the military seized power in a coup and imposed a nightime curfew, official figures showed on Friday.

Foreign visitor numbers slumped 10.6 per cent last month compared with a year earlier, to roughly 1.74 million people, the Tourism and Sports Ministry reported.

For the first five months of 2014, arrivals were down nearly 6 per cent year-on-year.

"The reasons are political rallies, the imposition of emergency rule, martial law and the curfew," said Mr Arnupap Gaesornsuwan, director-general of the ministry's Tourism Department.

Drawn by its sun-kissed beaches, tranquil temples and racy nightlife, the kingdom welcomed a record 26.5 million foreign visitors in 2013.

But months of street protests and political bloodshed have tarnished Thailand's reputation as the "Land of Smiles".

Mr Arnupap said the government had lowered its forecast for tourist arrivals this year to 25.9 million, down from an initial target of 28 million.

The army takeover has prompted a flurry of warnings from foreign governments about travelling to the South-east Asian holiday hotspot.

The ruling generals have curtailed civil liberties by banning public protests, censoring media and temporarily detaining hundreds of critics for questioning.

But tourists have been largely unaffected by the bloodless coup, apart from the curfew and, in some cases, issues with their travel insurance coverage.

The curfew was relaxed to midnight until 4am late last month, and lifted on Tuesday in the beach resorts of Pattaya, Koh Samui and Phuket in an attempt to lure back tourists.

The coup makers said on Friday they were planning to scrap the curfew soon in four more tourist destinations - Hua Hin, Cha-Am, Hat Yai and Krabi, and lift the measure for the rest of the country as soon as possible.

Thailand's economy shrank 0.6 per cent year-on-year in the first three months of 2014, partly because of the tourism slump, and many forecasters expect a second-straight quarterly contraction, tipping the kingdom into recession.