National Party Leader John Key is due to meet Canadian Prime Minister Stephen Harper and United States Deputy Secretary of State John Negroponte when he visits North America next week.

"This visit to both countries is all about building long-term, durable relationships," says Mr Key.

"The United States and Canada are two of our most important bi-lateral relationships, and it is in the interests of all New Zealanders that the relationships are maintained and enhanced."

Mr Key leaves next Monday evening, and returns on Sunday July 1. He will be accompanied by National's Foreign Affairs spokesman Murray McCully, Trade spokesman Tim Groser, and a staff member.

He is due to meet State Department number two, Deputy Secretary Negroponte, on Tuesday, June 26 (local). He is also due to meet Assistant Secretary of State for East Asian and Pacific Affairs, Christopher Hill, earlier that day.

In addition, Mr Key is due to meet White House Environmental Quality Council chairman James Connaughton, and Deputy US Trade Representative Karan Bhatia.

Mr Key will also visit Ottawa to meet Canadian Prime Minister Stephen Harper. This is scheduled for Wednesday June 27 (local).

This is Mr Key's first official visit to the US and Canada as Leader of the Opposition. He visited Australia last December and met Australian Prime Minister John Howard and a number of other senior Ministers.

Other details of the visit are still subject to final confirmation. It is expected that Mr Key's itinerary will also include appointments at the Pentagon, National Security Council, and with a number of members of Congress.