China on Friday downplayed the impact of Sri Lanka's presidential election upset, dismissing suggestions that the stunning win by Maithripala Sirisena could shake up Beijing's plans in the Indian Ocean.

Sirisena on Thursday ousted longtime president Mahinda Rajapakse, who has relied heavily on Chinese funding for major infrastructure work in his island country.

Among the major projects is Colombo Port City, Sri Lanka's largest single foreign investment, which is under construction alongside an existing giant Chinese-built container terminal.

Beijing has been accused of seeking to develop facilities around the Indian Ocean in a "string of pearls" strategy to counter the rise of its Asian rival India and secure its own economic interests.

At a regular briefing, Chinese foreign ministry spokesman Hong Lei congratulated Sirisena on his win and said that cooperation between the two countries "has been deepening".

"Our friendship runs deep, and successive governments of Sri Lanka have had a friendship policy towards China," Hong said, adding: "We have a good momentum there."

"We hope and we believe the new Sri Lankan government will carry on the friendly policies towards China and lend their support to relevant projects to make sure these projects are successful," he added.

Sri Lanka is a midway point on one of the world's busiest international shipping lanes, which Beijing wants to develop as a "maritime silk road" for the 21st Century.

During a visit in September, Chinese President Xi Jinping launched construction of the $1.4 billion Colombo Port City, which will give Beijing a firmer foothold in the region.

As part of the deal, China is set to gain ownership of one third of the total 233 hectares (583 acres) of reclaimed land that the new facility will occupy.

But the project has drawn strong criticism from Sri Lanka's now-triumphant opposition, which last month accused China of destroying the island's pristine beaches and warned Beijing its investment could be in jeopardy should they return to power.

Opposition leader Ranil Wickremesinghe -- who is expected to return to his former post as prime minister under the new government -- has said his party would take a fresh look at "haphazard reclamation" of land near Colombo harbour for a new port city.

Hong maintained that China and Sri Lanka would "accommodate each other's interests" and that progress would be based on consensus.