Vietnamese shares struggled to extend gains in the early session, even though energy stocks were up, following investors' cautiousness ahead of Thursday's referendum on Britain's membership in the European Union.

The benchmark VN Index on the HCM Stock Exchange and the HNX Index on the Ha Noi Stock Exchange inched up 0.2 per cent each to close at 629.31 points and 84.69 points, respectively.

The energy sector lifted markets as oil prices bounced back from Tuesday's fall. US crude West Texas Intermediate (WTI) advanced 0.7 per cent to trade at US$50.19 per barrel.

On the southern bourse, PetroVietnam Gas Corp (GAS) gained 0.8 per cent and PetroVietnam Drilling and Well Service Corp (PVD) rose 1.9 per cent.

On the northern market, PetroVietnam Mud Drilling Corp (PVC) added 1.2 per cent and PetroVietnam Technical Service Corp (PVS) increased by 1.6 per cent.

Gains were also seen in dairy firm Vinamilk (VNM) and consumer goods producer Masan Group (MSN), which edged up 0.7 per cent each.

Investors, however, remained cautious ahead of Thursday's referendum, during which British voters will decide whether or not Britain will remain a European Union member.

Most of the nine listed banks remained flat and declined from Tuesday's prices, including Asia Commercial Bank (ACB), Eximbank (EIB) and Vietcombank (VCB).

Investors traded 86.6 million shares worth VND1.6 trillion ($72 million).

Source VNS