The Welsh government has backed the idea of introducing a tax on sugary drinks in the battle to cut rates of obesity and diabetes.

The finance minister, Jane Hutt, told the Welsh assembly that a levy could “add to the armoury of initiatives” to tackle the problems associated with sugary drinks. She said: “There is a strong case in principle for developing proposals in relation to a levy.”

Hutt said Wales could draw on the experiences of countries such as Mexico, France and Hungary, which have introduced similar taxes, but said it would be challenging to draw up a law that worked. Previously the Labour-led government had criticised plans to use the tax to pay for extra doctors as it was feared this would be effectively encouraging people to consume more fizzy drinks.

Plaid put forward a motion to the assembly calling for the government to bring forward proposals that would allow the next administration, after next year’s elections, to introduce a levy on sugary drinks. Both Labour and the Liberal Democrats supported the motion.

Plaid Cymru’s health spokeswoman, Elin Jones, said: “The national assembly for Wales is in favour of Plaid Cymru’s proposal for a pop tax. More and more organisations and experts have called for a tax on sugary drinks, including celebrity chef Jamie Oliver who has supported Plaid Cymru’s policy.

“Excess sugar consumption is one of the biggest risks to public health, and unless we take action the threat will continue to grow. I’m pleased that the Welsh government has today U-turned and supported our proposals.”

Elin Jones (@ElinCeredigion) Really pleased to get majority support now for @Plaid_Cymru poptax https://t.co/VuqQHIBv9f

The Conservatives’ health spokesman, Darren Millar, spoke against the idea during the debate. He said: “A Tango tax is not the answer to the public health crisis that is growing in Wales. The reality is that only 3% of the calories consumed in Wales come from soft drinks. If we think we are going to make a huge difference from taxing sugary drinks then we are hugely mistaken.”

He said soft drinks manufacturers had made huge inroads into sugar reduction, and he asked whether other drinks containing sugar – from fruit juice to milk drinks and beer – would also be taxed. “If you think adding pennies is going to discourage youngsters across this country from buying the occasional can of Coke or the occasional Fanta, I think you are very much mistaken,” Millar said.

There have been a number of eyecatching health initiatives developed or considered in Wales in recent months. This month it became the first part of the UK to adopt a “deemed consent” system for organ donation. People aged 18 and over who have lived in Wales for more than 12 months and who die in the country will be regarded as having consented to organ donation unless they have opted out.

The government also attracted headlines – and a great deal of criticism – in the summer when it said it wanted to ban e-cigarettes from all enclosed public spaces. This week the health minister, Mark Drakeford, announced plans to water down the idea by introducing a ban in places where there is a “potential risk” to children, such as schools, restaurants and on public transport.

It will be difficult in practice to introduce a sugary drinks levy as, though the Welsh government is being given more scope to introduce its own taxes, they would have to be approved by the UK parliament, which is not supportive of such a tax.