Washington: Osama bin Laden is alive and hiding, constantly moving between Pakistan, Pakistan-occupied Kashmir (PoK) and Eastern Afghanistan, the author of a 1999 biography of the al-Qaida leader has said.

"To the best of my knowledge, he is alive," Yossef Bodanski, a consultant to the US House of Representatives, told Fox News.

Bin Laden "is very much in control of his people, of the activities of the elite network that answer to him or admire him", he said on July 21.

Bodanski said Pakistani intelligence services "are actively supporting and assisting" bin Laden, who travels with an all-male inner circle of less than 12 commanders and 30-60 bodyguards.

"There is communication with his people. He has maintained communication with his supporters."

Bodanski said bin Laden "is shuttling between the Afghanistan panhandle, Pakistan- occupied-Kashmir (PoK) and certain segments of the North Western part of Pakistan and sometimes crossing into Afghanistan."

The elusive bin Laden was seen for the last time two to three weeks ago by an unnamed "credible source", he said.

"He's trying to dodge enemies, and the level of activity is such that he cannot have vanished completely," he said. "We don't know enough in real time in order to be able to get him, but we have a fairly good idea of what he's doing."