HANOI Dec 25 - Singha Asia Holdings Pte Ltd on Friday signed a $1.1 billion strategic deal with Vietnam's Masan Group to buy stakes in two of the consumer goods firm's unlisted units, the companies said.

Singapore-based Singha Holdings would buy 25 percent of Masan Consumer Holdings and 33.3 percent of Masan Brewery in a deal that aims to help Singha expand in Vietnam and give Masan a foothold in Thailand.

Vietnam is the third-largest beer consumer in Asia behind Japan and China, consuming 3 billion litres in 2013 and out-drinking wealthier Southeast Asian peers like Thailand, government data showed.

"Masan's extensive distribution platform touching every corner of Vietnam will help Singha reach a market of 90 million people that is expanding quickly," chief executive Palit Bhirombhakdi of Singha Asia Holdings said in a statement.

Singha Asia Holdings is a unit of Thailand's Boon Rawd Brewery, controlled by the family of Santi Bhirombhakdi, Thailand's seventh richest man according to Forbes Magazine.

The Bhirombhakdi family also owns businesses in property , retail, fashion, food and consumer goods and is the latest among Thailand's wealthy elite to make inroads into the Vietnam, which is posting strong economic growth and has a middle class expanding at one of Asia's fastest rates.

Masan Group is one of Vietnam's biggest listed firms and has businesses in consumer goods through Masan Consumer Holdings, which owns 66.7 percent of newly established Masan Brewery, and mining firm Masan Resources.

"The list of products and operating platform of Singha could help promote the growth of Masan in both Vietnam and other markets in the region," said Seokhee Won, deputy chief executive officer of Masan Group.

The deal is expected to be concluded in January 2016, the statement said.

Shares of Masan soared 6.38 percent on Friday to close above a three-month high at 70,500 dong ($3.13), Reuters data showed. ($1 = 22,540 dong)