Prices of rice exported from top Asian hubs eased slightly this week as the sharp rally driven by India's export curbs took a toll on demand and made buyers hesitant to ink new deals.

Top exporter India imposed a 20% duty on exports of parboiled rice on Aug. 25 in addition to existing curbs on the non-basmati white variety, at a time when prices where already near 12-year highs.

India's 5% broken parboiled variety was quoted at $525 to $535 per metric ton, slightly lower than the record high of $520-$540 touched last week.

"The export duty has added fuel to rising prices. Buyers are not accepting the elevated prices," said an exporter.

Neighboring Bangladesh meanwhile planned to soon lift a ban on aromatic rice exports, given good domestic reserves and record crops, a commerce ministry official said.

Bangladesh usually exports a small quantity of aromatic rice to the U.S., Britain and the Middle East.

Vietnam's 5% broken rice was offered at $630-$640 per metric ton on Thursday, its lowest in a month, and down from $640-$650 last week.

"Prices edge down so that supply can meet demand, as buyers are not willing to pay high prices," a Ho Chi Minh City-based trader said.

Preliminary shipping data showed 128,050 tons of rice were to be loaded at Ho Chi Minh City port during Sept. 1-13, with most of it heading to the Philippines, Indonesia and Malaysia.

Vietnam will soon sign an inter-government rice trade agreement with the Philippines to ensure food security for both countries, Vietnamese authorities said on Thursday.

Thailand's 5% broken rice prices also eased to $620 per metric ton from $635 last week.

Supply was gradually coming in and prices coming down due to a weaker baht, a Bangkok-based trader said.

Another trader said buyers were delaying decisions since prices were high. (Reporting by Rajendra Jadhav in Mumbai, Khanh Vu in Hanoi, Chayut Setboonsarng in Bangkok, and Ruma Paul in Bangladesh; Editing by Arpan Varghese and Jan Harvey)