The leader of the US House of Representatives has urged President Barack Obama to deploy troops along the Mexican border to help curb a surge of undocumented Central Americans migrating to the US, calling it a "national security and humanitarian crisis".

In a letter to the president issued on Friday, John Boehner blamed Obama administration policies for the huge increase in migrants, a bulk of whom are children that travelled unaccompanied by adults and in search of better lives in the US, from Guatemala, El Salvador and Honduras, and called on the president to act against the influx.

"While we understand that many of these individuals are coming to this country to escape violence and hardship in their home country, the current climate along the border and our enforcement policies are only encouraging them to risk their lives and those of their children.

John Boehner, US House Speaker

Tens of thousands of children from Central American countries, some as young as four-years-old, have been detained after crossing into the US under false promises by traffickers that they would be allowed to stay in the country once they reached it.

The US Department of Homeland Security estimates that 47,000 youths have been detained since October last year, a 92 percent increase over the same period a year earlier.

Many of the migrants are consigned to improvised holding centres with poor conditions, sleeping on floors and facing little food provisions.

Boenher's letter underscores that the issue has increasingly become a political problem for the Obama administration, which had hoped to spend the spring and summer pressuring House Republicans to pass comprehensive immigration legislation but is now increasingly occupied with the immigration issue.

Boehner said the US State Department should work with Central American nations to help speed processing times to return children and families to their countries and to make sure that people know of the dangers of heading north.

"The policies of your administration have directly resulted in the belief by these immigrants that once they reach US soil, they will be able to stay here indefinitely," Boehner wrote.

'Aggressive action'

"While we understand that many of these individuals are coming to this country to escape violence and hardship in their home country, the current climate along the border and our enforcement policies are only encouraging them to risk their lives and those of their children. It is time that we confront the crisis along the border head-on through immediate and aggressive action."

The US Border Patrol says the number of minors coming from Guatemala, El Salvador and Honduras has soared more than 1,000 percent.

Administration officials have said it's largely because of conditions in their home countries, but there's also a belief among some of the migrants that they would be allowed to stay once in the US.

The White House had no immediate response to Boehner.

Source: Agencies