Over 10 million people could die from smoking-related diseases within 20 years, the former head of the World Health Organization has said.
Dr Brundtland stepped down as WHO chief in May
Dr Gro Harlem Brundtland, who retired as WHO director general in May, predicted deaths will double unless governments act to cut smoking.
Smoking-related diseases currently claim the lives of five million people each year.
However, more and more people in the developing world are taking up the habit, sparking fears of an impending public health time bomb.
Dr Brundtland urged governments to implement the WHO's Framework Convention on Tobacco Control.
The landmark treaty was agreed by the WHO's 192 member states in May.
The pact, which took years of negotiations, requires countries to ban or impose tough restrictions on tobacco advertising, sponsorship and promotion within five years.
It also lays down guidelines on health warnings to be carried on cigarette packets, recommends tax increases on
tobacco products and calls for a crackdown on cigarette smuggling, amongst other measures.
Dr Brundtland said introducing these measures would help to save millions of lives.
"Ten million people will die every year from tobacco, 20 years from now, unless real changes are made," she said.
"This treaty will help to curb the epidemic. It will definitely help to reduce levels of consumption. There will be fewer new smokers and there will be more smokers who choose to quit.
"We know that higher prices, higher taxes, advertising bans - these are all political efforts that work.
"It has been seen in countries where this has been done."
Dr Brundtland described the treaty as a "watershed".
"It is the first international health treaty," she said.
"It is a watershed because now all countries have an international standard to go by and those who sign and ratify it also have a legal obligation to follow the text of that convention which means policies will be changed, laws will be passed, budgets will be different.
"Countries will be following a common prescription about what is needed to be done to abate the tobacco pandemic or epidemic that is now hitting the developing world."
In an interview with the BBC World Service's Health Matters Dr Brundtland also urged western countries to increase the amount of money they donate to international health.
"Some countries in the past two or three years have started slowly increasing their development cooperation budget which is a wonderful thing to see after many many years of reduction," she said.
"More resources are flowing into poor countries but also more resources are being used.
"But much more needs to be done and this is an issue for the countries of the world."
This story is featured in the radio programme Health Matters on the BBC World Service.
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