Export prices of rice from Vietnam extended gains to a fifth week on Thursday, as high domestic demand continued to keep procurement costs elevated, while limited supplies pushed up rates for top exporter India.

Vietnam's 5% broken rice rose to a near three month high of $430-$435 per metric ton from $425-$430 a week earlier.

"The government's move to top-up the national reserves has supported domestic and export prices, but incoming supplies from an ongoing mini harvest will keep prices from rising further," a trader based in Ho Chi Minh City said.

Farmers in the country's rice bowl Mekong Delta have started the autumn-winter harvest, which is expected to reach a peak late this month or early next month.

Rates for India's 5% broken parboiled rice variety edged up to $360 to $363 per metric ton from the $358-$363 quoted last week.

"We are at the fag end of the season, and supplies are limited," a Mumbai-based exporter said, adding that new crop would become available from November.

Traders in neighbouring Bangladesh, meanwhile, continued to mostly buy rice from India through land ports, and the government expected elevated domestic prices to ease ahead.

In Thailand, prices for the 5% broken rice variety rose to $385-$420 per metric ton from $385-$386 last week, driven by a slight strengthening in the baht. A stronger baht translates to higher export prices in U.S. dollars.

There was, however, no change in overseas demand.

Thailand, which exported about 3.7 million metric tons of the grain between January and September this year, was on track to export six million metric tons by the end of the year due to an anticipated uptick in demand from returning buyers.