Dr. Derek Yach, the World Health Organization's former anti-tobacco chief who oversaw the drafting of the treaty, hailed the accord, known as the Framework Convention on Tobacco Control, as a first step.
However, he told The Associated Press in an exchange of e-mails that the treaty lacks what are known in United Nations jargon as "protocols" — additional agreements that toughen specific areas of a looser accord.
"The Framework without protocols is toothless," said Yach. "Yet even preliminary work on these is over a year from even being discussed, let alone planned for."
Now professor of global public health at Yale University, Yach was deeply involved in four years of often bitter negotiations brokered by the U.N. health agency.
The treaty, which was finalized in May 2003, aims to substantially reduce the number of deaths from tobacco-related illness — like cancer and heart disease — which the WHO estimates kill one smoker every 6.5 seconds.
Of the 168 countries that signed the accord, only 57 have so far ratified it. China and the United States are among those who have not ratified the pact.
The world has an estimated 1.2 billion smokers and WHO surveys show that smoking rates among 13- to 15-year-old children are about 20 percent. Health officials say they fear those figures will explode as the world's population grows.
By 2010, the annual death toll is expected to double to 10 million — with 70 percent of the victims in developing countries least able to pay for treating smoking-related illnesses.
The treaty, known as the FCTC, requires its ratifiers to restrict tobacco advertising and sponsorship, put tougher health warnings on cigarettes and limit use of language such as "low-tar" and "light." They are to enact price and tax hikes, create controls on secondhand smoke and sales of cigarettes to youngsters, and clamp down on smuggling.
But governments, particularly those with few anti-tobacco policies, need clear, exact guidelines on what they should do, Yach said.
"Evidence suggests that the only way to have a rapid impact on deaths from tobacco is to step up cessation efforts and combine them with smoke free policies," he said. "However, the language of the FCTC is relatively weak on these issues."
With the new rules in place, studies suggest the reduction in demand for cigarettes would only fall 1 percent to 2 percent a year, WHO officials have said.
"No targets were ever discussed for the FCTC, so we do not have a sense of what constitutes success," Yach said. He also said poor countries will need substantial financial help in implementing the treaty's provisions.
Ratifying countries that fail to enact reforms face no penalties but will have their record examined at U.N. anti-tobacco conferences, the first of which is set for February 2006.
"Now that this global treaty has become international law, it is no longer business as usual for 'Big Tobacco,'" said Akinbode Oluwafemi of Environmental Rights Action, a Nigerian-based group.
Tobacco companies reportedly lobbied against the treaty during negotiations but have since said they have no objection to the pact despite their discontent over being excluded from the formal treaty talks.
"Tobacco is harmful to health and as a responsible tobacco group, we have long recognized the right of national governments to regulate it," said Emily Brand, a spokeswoman for British American Tobacco Ltd.