US President George W Bush has said he supports immigration to the US from Mexico and Central America, so long as it is orderly.
The three leaders visited the Mayan ruins at Chichen Itza
Mr Bush was speaking during talks with his Mexican counterpart, Vicente Fox, at the start of a two-day summit in Cancun, also involving Canada.
Mr Bush said he was not in favour of allowing illegal immigrants to be put on a fast-track to US citizenship.
But he promised to try to push through legislation on a work-permit system.
"I told the president that I am committed to having a comprehensive immigration bill on my desk," he said.
"And by comprehensive, I mean not only border security - a bill that has border security in it, a bill that has interior enforcement in it, but a bill that has a worker permit programme in it.
"And that's an important part of having a border that works."
Mr Bush did not give a timetable for reform, which faces what he called a cumbersome process in the US Congress, where hardline conservatives are strongly opposed to it.
'Safe border needed'
Mr Fox, meanwhile, said Mexico and Central America had a role to play in tackling illegal immigration.
"We want a safe border. We want it for the good of our people and also for our relationship with the United States," he said.
However, he ruled out any possibility that Mexico would try to prevent migrants from crossing the border.
Mexico's navy has sealed off the area around the summit venue
"We can't infringe upon the right of people to move freely within our territory," Mr Fox said.
Mr Bush's proposed reforms would allow illegal immigrants to register for legal status and eventually for US citizenship.
His opponents in the House of Representatives have approved a bill making unapproved US entry a crime along with plans to build a fence along the Mexican border to keep immigrants out.
The measure touched off mass protests in US cities and now the Senate is working on a possible compromise that would reinforce border security while allowing work visas and eventual residency for some immigrants.
In other developments at the summit:
- Mr Fox said he was preparing to extradite at least 24 drug traffickers to the US
- Mr Bush said he would resume negotiation with Canada on softwood lumber import tariffs
Mr Bush is also expected try to address Canada's concerns over an American plan to require Canadians to show passports and not merely driver's licences when they cross the border
All three leaders wish to repair relationships strained by the US invasion of Iraq - a decision both Mexico and Canada opposed.