GENEVA, March 7 (CNA) - Swiss voters on Sunday (Mar 7) narrowly backed a free trade deal signed with Indonesia, opening up a vast potential market with the world's fourth most populous country.

Controversy surrounding the importation of Indonesian palm oil and its sustainability fuelled enough concern in Switzerland to trigger a public vote on the agreement.

But the deal scraped through the public approval test with 51.7 per cent of the vote, on a 51 per cent turnout.

Supporters voiced relief at the result but said they would have to be more sensitive to environmental issues in any future votes on trade agreements.

Under the deal, tariffs will be gradually removed from almost all of Switzerland's biggest exports to Indonesia, while the Swiss will abolish duties on Indonesian industrial products.

Anyone importing Indonesian palm oil must prove that it meets certain environmental and social standards.

The agreement was signed in 2018 and approved by the Swiss parliament in 2019, but opponents were especially critical of Bern's move to reduce palm oil import duties and secured a public vote on the deal.

Palm oil is a key ingredient in a wide range of products from food to cosmetics, but it has long been controversial.

Environmentalists say it drives deforestation, with huge swathes of rainforest logged in recent decades to make way for plantations.