The US has said there is evidence linking al-Qaeda to last week's twin attacks on Israelis in Kenya where authorities have denied allegations they ignored warnings of the strikes.
Israel also had warnings before a suicide attack killed the three bombers, three Israelis and 10 Kenyans at an Israeli-owned hotel in the resort of Mombasa on Thursday. An almost simultaneous missile attack narrowly missed an Israeli airliner taking off nearby. A missile launcher used in that attack has been linked to al-Qaeda, a US official said.
Washington also sees as credible a purported al-Qaeda statement claiming responsibility for the attacks. "The fighters of al- Qaeda return to the same place where the Crusader-Jewish coalition was hit four years ago," said the statement on the internet, referring to the bombings of the US embassies in Kenya and Tanzania that killed 224 people.
In Washington, a US official said the statement, signed by the "Political Office of Qaeda al-Jihad", was being seen as credible. He said there was reason to believe al-Qaeda involvement.
The Kenyan government denied allegations that it failed to act on warnings before the attacks and ignored information that al-Qaeda suspects had infiltrated Kenya from lawless Somalia.
But a senior Kenyan military intelligence official said the authorities had done little after receiving warnings from foreign intelligence services including those of Britain and Australia. "Little or no action was taken to prevent the attacks," he said.
Kenyan police have held six Pakistanis and four Somalis for questioning since Thursday's attacks, but say they have found no links to al-Qaeda or to al-Itihad.
In Jerusalem, an official said Israeli military intelligence had warnings that al-Qaeda was preparing for a possible strike in Kenya before last week's attacks.
Brigadier-General Yossi Kuperwasser told lawmakers in a closed-door session on Monday that Israeli intelligence had received information about al-Qaeda reconnaissance in Kenya, parliament spokesman Giora Pordes said.