WASHINGTON — The United States and Mexico have agreed to boost efforts to crack down on the production of methamphetamines by Mexican drug cartels along their common border, US authorities said Thursday.

The memorandum of cooperation signed by the two sides calls for improved sharing of intelligence and joint law enforcement training, the US Drug Enforcement Administration said.

Authorities seized 7.3 tonnes of methamphetamines on the US-Mexico border last year, nearly double the haul in 2009.

Between 2010 and 2011, the seizure in Mexico of chemicals used to manufacture the synthetic drug rose 1,000 percent.

"With the majority of methamphetamine in the US being produced by Mexican drug organizations operating on both sides of the border, it is essential for our two countries to target the problem together," DEA administrator Michele Leonhart said.

Leonhart and Mexican Attorney General Marisela Morales Ibanez signed the memorandum.

Morales Ibanez called the deal an "unprecedented event because both of our countries are signing the very first international instrument that will help fight the manufacturing of synthetic drugs in clandestine laboratories."

The US State Department has earmarked $12 million for Mexico under the Merida Initiative, an anti-drug effort linking US, Mexico and Central American countries with the aim of battling trafficking and organized crime.

More than 50,000 people have been killed in drug-related violence across Mexico since 2006, when the military was ordered to take the lead in a crackdown against the country's powerful drug cartels.