The leaders of the United States, Mexico and Canada vowed to enhance cooperation in combating an expected spread of H1N1 influenza virus this fall.

"In anticipation of a possible fall wave of flu due to the 2009 H1N1 virus, we will look to enhance our exchange of information, ensure common understanding on the effectiveness of public health measures and share expertise," the leaders said in a statement issued at the end of a summit in Guadalajara.

They also said they would put in place infrastructure to cooperate on greenhouse gas emissions trading as part of efforts to fight climate change.

"We will build capacity and infrastructure with a view to facilitate future cooperation in emissions trading systems, building on our current respective work in this area," the three countries said in a statement.

They also said they would work toward reducing emissions from the transport sector, including "by striving to achieve carbon-neutral growth in the North American aviation sector in the context of global action."

• Agenda at Mexico Summit