* Will expand transport, food, payments networks in Vietnam

* Investment a reflection of Grab's commitment to Vietnam - exec

* Last month, Grab unveiled $2 billion plan in Indonesia (Adds details, background)

By Khanh Vu and Phuong Nguyen

HANOI, Aug 28 (Reuters) - Ride-hailing firm Grab said on Wednesday it will invest $500 million in Vietnam over the next five years to expand its services in the Southeast Asian country.

The company will expand its transport, food and payments networks in the country, Grab said in a statement.

"This investment is a reflection of our redoubled commitment to Vietnam," Russell Cohen, head of Grab's regional operations, was quoted as saying in the statement.

"The country's rapidly developing economy and emerging middle class population makes it ripe for the adoption of digital services," he said.

Reuters first reported news of the Vietnam investment earlier this week. Grab President Ming Maa told Reuters in an interview that "we're very excited about Vietnam. We see very similar characteristics to Indonesia".

Last month, Grab unveiled a plan to invest $2 billion in Indonesia, the region's most populous market, where it aims to build a next-generation transport network and transform how critical services such as healthcare are delivered.

Its decision for additional investment in Vietnam comes as the ride-hailing market in the country becomes more competitive with the participation of Indonesia's Go-Jek and Vietnam's Be.

"Competition in ride-hailing will become fiercer," said Ho Chi Minh-based economist Bui Quang Tin. "The size of the investment means Grab will be able offer heavy discounts even if it risks losses in short term," he added. (Reporting by Khanh Vu and Phuong Nguyen; Editing by Himani Sarkar)