New Delhi, Oct 12 (IANS): Amid China's increased assertiveness in the region, India and Vietnam Wednesday signed an extradition treaty and decided to launch a biennial security dialogue to expand their their strategic partnership.

The two countries also decided to more than double their bilateral trade from $2.7 billion to $7 billion by 2015 and agreed to boost the two-way investment.

In a subtle message aimed at Beijing whose relations with Hanoi are under strain, Prime Minister Manmohan Singh called India's strategic partnership with Vietnam "a factor of peace, stability and development" in the Asia-Pacific region. However, he added that the relationship stood "on its own merits".

"A strong India-Vietnam relations is a factor of peace, stability and development in the Asia-Pacific region. It stands on its own merits. The president's visit has give a new thrust and direction to this partnership," Manmohan Singh said at a joint press conference with Vietnamese President Truong Tan Sang.

The two sides inked a crucial extradition treaty and agreed to boost cooperation across a broad spectrum of areas, including trade, energy, science and technology, IT and conservation and restoration of Indian cultural relics in Vietnam.

"We have instituted a mechanism of a biennial dialogue on security issues between our ministry of home affairs and its Vietnamese counterpart. The extradition treaty signed today will provide a legal and institutional basis for our cooperation," said Manmohan Singh.

Manmohan Singh also underlined that India and Vietnam were maritime neighbours in the region and would work together to confront security challenges from terrorism, piracy and natural disasters.

"We have to work together to ensure the safety and security of vital sea lanes of communication and continue exchanges in this fields in the future," he said.

The prime minister's comments obliquely alluded to Chinese objections to India's oil exploration deals with Vietnam in its territorial waters in South China Sea, which Beijing claims in full.

The two sides set the target to increase bilateral trade to $7 billion by 2015 and agreed to work towards an early finalisation of the India-ASEAN Free Trade Agreement in Services and Investment.

"I conveyed to the president that we are committed to greater investment flows between our two countries," said Manmohan Singh.