The FBI is stepping up its hunt across Africa for suspects wanted in connection with their investigation into the recent suicide attacks on New York and Washington.

We want to determine the motive of the writers of these graffiti and who they are. It could be an important bait

Kenyan intelligence source

Kenya, Uganda, Tanzania and South Africa have all been given long lists of names of people believed to be linked to the prime suspect behind the attacks, the Saudi-born militant Osama Bin Laden.

A list of about 200 suspects has been handed to Kenya, says the Daily Nation.

United States investigators are also reported to be scrutinising banking transactions in Kenya's second city of Mombasa.

Bin Laden Street

Kenyan intelligence officials say they are investigating pro-Bin Laden graffiti in Muslim areas of Mombasa, according to the French news agency, AFP.

AFP says that one street has unofficially been renamed Bin Laden Street.

"We want to determine the motive of the writers of these graffiti and who they are. It could be an important bait", a senior National Security Intelligence Service (NSIS) source told AFP.

Border controls between Kenya and its East African neighbours Tanzania and Uganda have also been tightened.

More than 200 people died in bomb attacks on US embassies in Kenya and Tanzania in 1998, which were also also linked to Bin Laden.

Officials from the FBI and the CIA have been in Sudan for a year, where Bin Laden was based until 1996.

Complex task

Following the 1998 attacks, the US launched missile strikes on a pharmacutical factory in Khartoum.

Thousands died in the attacks

Bin Laden's organisation is thought to be a loose coalition of groups operating across continents with US officials believing that his associates may operate in more than 40 countries.

Tracking the people, the front organisations and the financial infrastructure of this network, is an immensely complex task.

Tanzanian police told The East African weekly newspaper that of 60 names given to them, none were Tanzanian citizens.

South African and Ugandan police have not divulged how many names they have been given.

Life sentence

The US has pledged to protect and support African states that co-operate in its international campaign against terrorism.

The US is understood to be seeking varied support from different states, from diplomatic and intelligence help to providing troops, bases and ports.

South Africa previously helped US intelligence track down Tanzanian Khalfan Mohamed, who was traced through an asylum application following the embassy bombings.

He received a life sentence earlier this year for the bombing of the US embassy in Dar es Salaam.