Kenya's Government says it has intelligence information suggesting the al-Qaeda network is planning another attack in the country or the wider East African region.
Kenya's tourist industry was hit by the Paradise hotel attack
Security Minister Chris Murungaru said he believed an attack was due to be carried out before the end of the month.
A statement said Kenyan security forces had been put on high alert and there would be a greater security presence around vital installations in the near future.
"This information is not intended to cause any panic. It is just to inform the public that the threat still exists and we must deal with it as such," he said.
Earlier, the minister released the picture of a Comoran national.
He is suspected of being involved in the 1988 bombing of the United States embassy in Nairobi and last year's attack on the Israeli-owned Paradise Hotel near the coastal town of Mombasa when 15 people, mainly Kenyans, were killed.
More than 200 Kenyans have died in terror attacks
The minister said the suspect was believed to have acquired Kenyan identity papers and to be operating between neighbouring Somalia and Kenya.
Another suspect linked to the 1998 terror was sent to the United States for trial in March this year.
In 2001, a court in New York found four people guilty of the attacks.
The UK and US Governments have issued advice to their citizens this year warning them that the al-Qaeda network or its sympathisers could attack countries in East Africa.