The US embassy in Cairo warned its citizens on Tuesday to exercise caution in Egypt following a series of attacks including a bombing that killed a French tourist last month, saying more attacks may be planned.
A bombing in a popular Cairo tourist area that is home to the 14th century Khan al-Khalili market killed a French teenager on Feb. 22, the first deadly attack on tourists in Egypt since bombs hit a Sinai peninsula resort town in 2006.
Days later an American teacher was stabbed nearby by an attacker who told police he was motivated by a hatred of foreigners, particularly after Israel's recent offensive in the Gaza Strip. On Saturday, an attacker threw a firebomb at a crowded metro rail station in the capital, but no one was hurt.
"These events do not appear to be connected, but there is some indication that additional incidents are planned," the US embassy said in a warden message to its citizens.
It added that the Egyptian government had stepped up security in downtown Cairo, around major tourist sites and at public places like shopping centres. The message urged Americans to take care and "practise good personal security measures".
Islamist militants have hit Egypt's tourist industry in recent years through bomb and shooting attacks. Attacks on tourists are embarrassing for the government, which tries to project an image of security and stability.
There has been no claim of responsibility for the Feb. 22 bombing. Police detained 13 people for questioning, and have released all but two. No one has been formally charged.
The Egyptian government, an ally of Washington, has faced heightened domestic discontent in recent months over its enforcement of an Israeli blockade on Hamas-run Gaza, especially during the Israeli offensive that ended on Jan. 18.