Sri Lanka and Pakistan signed six agreements including one on atomic energy Monday, the two countries' leaders said, as the strategically important island looks to build its first nuclear plant.

Details of the agreement were not immediately available but it comes after Sri Lanka signed a pact with India in February to build its atomic energy infrastructure, including training of personnel.

Sri Lanka's new president Maithripala Sirisena swept to power in January, ending a decade of rule by Mahinda Rajapakse, and has moved to reduce China's influence in his country, which had irked India.

His arrived in Pakistan Sunday for a three-day state visit has been watched by observers for clues over any further changes in Colombo's foreign policy.

Pakistan and Sri Lanka have traditionally enjoyed strong ties, particularly over defence, with Islamabad providing military assistance during the war against Tamil Tiger guerrillas that ended in 2009.

Speaking at a press conference with Pakistan's Prime Minister Nawaz Sharif, Sirisena said: "At critical moments in our post-independent histories we have stood in solidarity with each other," adding he was "profoundly grateful for the strong support in the fight against terrorism" by Pakistan.

"We discussed regional and international agreements and signed six agreements in the fields of disaster management, sports, shipping, atomic energy... and in narcotics and academic cooperation," he added.

Pakistan currently has three operational nuclear plants generating a total of around 740 MW of power and has begun work on two more, including a 2,200-megawatt station to be built with Chinese technical assistance on the Arabian Sea coast at Paradise Beach, 40 kilometres (25 miles) west of Karachi.

Earlier Sharif had spoken of his desire to improve trade and economic relations.

Sirisena will also meet Pakistan's President Mamnoon Hussain during his visit and is due to leave Tuesday.