Vietnam said on Monday that it expects Russia to complete the construction of six submarines on time.

"We hope construction of six submarines will be completed by Russia on time, by the end of 2016," Vietnamese Prime Minister Nguyen Tan Dung told reporters during his visit to the Svetly shipbuilding yard in Russian western enclave of Kaliningrad.

Supply of the Russia-built submarines to Vietnam has been a manifestation of friendship and trust, he said, adding the aim of these orders is to "protect sovereignty of our country and its self-defense."

Russia will build six submarines of 636 class for Vietnamese navy in St.Petersburg and test them in Svetly.

A 636-class submarine is capable of carrying six torpedo launchers and mines. It can dive to 300-meter depth and is mainly intended for anti-shipping and anti-submarine operations.

Nguyen Tan Dung also said Hanoi would grant Russian warships a simplified procedure for calling at his country's ports. "Our country welcomes call-ins of Russian and other countries' warships in our ports for technical servicing," he said.

Russia used to maintain its naval base in the Vietnamese port of Kamran from 1979 to 2002.