Singapore will continue to support the growth of its energy and chemicals sectors as it seeks to keep its status as the region's leading player amid new challenges, said Prime Minister Lee Hsien Loong on Wednesday.

The Republic will upgrade facilities and infrastructure on Jurong Island, improve the skills of the country's workforce and adopt strategies to tackle climate change.

Mr Lee said: "Energy and chemicals contribute a third of our manufacturing output, with many spillover effects... Many Singaporeans have built successful careers in this industry here and overseas."

He was speaking at the opening of the multi-billion dollar expansion of ExxonMobil's chemical plant on Jurong Island on Wednesday morning.

The new facility is the American oil major's biggest investment here and is Singapore's largest-ever manufacturing investment.

It is also ExxonMobil's largest integrated petrochemical complex globally, and is well-positioned to serve growth markets in the region.

The oil major has invested more than US$10 billion in Singapore, including the chemical plant expansion. Industry experts have estimated the cost of the expansion to be at least several billion US dollars.

The new expansion more than doubles Exxon's existing annual petrochemical production capacity here, making this its largest-ever chemical expansion. For instance, its ethylene capacity has increased from 900,000 tonnes a year to about 1.9 million tonnes annually.

The Singapore plant now accounts for a quarter of its global chemical capacity.

ExxonMobil chairman and chief executive Rex Tillerson said at the opening: "In the years to come, this facility will benefit hundreds of millions of people, both citizens of Singapore and consumers around the world."

He added that Asia-Pacific will account for two-thirds of growth in global chemical demand.

Exxon has been in Singapore for 120 years and employs more than 3,300 staff here. Of these, 2,000 work at its refining and chemical production complex.