President Bush has been discussing the plan with Mexico's leader

A White House spokeswoman said the US would do all it could "to support Mexico's efforts to break the power and impunity of drug organisations".

The request, the first part of a $1.4bn initiative, is due to be discussed by Congress in Washington on Thursday.

Analysts have compared the package to the controversial, and much larger, aid the US gives Colombia to fight drugs.

But the BBC's Lourdes Heredia in Washington says that both the US and Mexico are keen to avoid too close an association with "Plan Colombia" because of the controversy it has generated.

'Positive effect'

If approved by Congress, the $1.4bn programme over two years would help pay for intelligence and training efforts, as well as equipment such as helicopters and boats.

Mexican troops have been deployed in the fight against illegal drugs

Mr Bush and Mexican President Felipe Calderon have been working on the details of the plan for several weeks, officials said.

"Already, President Calderon's decisive actions have had a positive effect in the United States," White House spokeswoman Dana Perino said.

"They have disrupted drug trafficker supply lines and have contributed to shortages in cocaine and methamphetamine supply across the nation."

Since taking office last December, Mr Calderon has sent nearly 30,000 troops and federal police across his country to battle the drug gangs and disrupt their activities.

Figures released earlier this month by US drugs tsar John Walters indicated the price of cocaine in 37 cities across the US has risen sharply since March and purity has declined, suggesting dealers' supplies are being stretched.

Ninety percent of cocaine entering the US comes through Mexico.

However, the crackdown has exacted a price in Mexico, where a brutal underworld struggle has left as many as 2,000 people dead, including more than 200 police officers, commanders and soldiers.