Washington: In a bid to avoid terrorists from entering the country, United States now has plans to station American inspectors at foreign airports to screen passengers before they board a US-bound plane, 'The Wall Street Journal' reported.

US Customs Chief Robert Bonner told the financial daily that the initiative, which was still being developed, would be aimed at identifying and catching possible terrorists before they board a US-bound plane.

The department of Homeland Security is considering seven specific sites world over to implement what is being called the Immigration Security Initiative, but officials have yet to seek support from the host countries, Bonner said.

"It will be voluntary," Bonner said adding, "nobody has to participate in these things unless they find it in their interests to provide better security." US officials have identified seven hub airports around the world Heathrow and Gatwick near London, Narita outside Tokyo, Charles de Gaulle airport in Paris, Frankfurt Main in Frankfurt, Mexico City International and Amsterdam's Schipol airport to implement the initiative.