In an unexpected divorce from 'Lady Nicotine,' the United States has announced its support for a campaign designed to combat tobacco use around the globe.

"We are going to support it -- much to the surprise of many around the world. We are not going to make any changes. We have no reservations. The US delegation here is in support of the tobacco treaty," Secretary of the US Health and Human Services Tommy G Thompson, announced in Geneva on Sunday.

A formal announcement in this regard would be made when he addresses the World Health Organisation later this week.

The treaty is viewed by some as the most important international public health effort ever undertaken.

It is designed generally to make it more difficult for cigarette companies to promote and sell their products worldwide, but especially in developing nations, including India and China.

Late last month, the US was accused of trying to sabotage the treaty when it formally asked all 171 members of the WHO to support its already-rejected position that each nation should have the right to opt out of any clause in the treaty that it found objectionable or unconstitutional.

The letters to foreign and health ministers, viewed generally as a blow to the tobacco companies which are heavy contributors to political parties in the US, said unless a 'reservations' clause was included in the treaty, the ability of the US to sign and ratify the treaty would be undermined.

However, the battle can be regarded as won only when the Senate ratifies the treaty. The tobacco lobby's clout is strong in the Senate.