There were five explosions in Morocco's business capital
Official advice to British visitors to Morocco has been revised after at least 41 people were killed in a series of suicide bomb attacks, the Foreign Office has said.
Those already in the country "should keep a low profile, avoid crowds and be especially vigilant in public places frequented by foreigners," a spokeswoman added.
The Foreign Office is not advising against travel to the country, but states that there is a "clear terrorist threat".
It said four Britons escaped unhurt when their Casablanca hotel was among the targets in Friday night's attacks.
Earlier on Friday the UK Government issued a new warning of a "clear terrorist threat" in six East African countries - Djibouti, Eritrea, Ethiopia, Somalia, Tanzania and Uganda.
It had already banned British flights to and from Kenya amid fears they could be targeted by the al-Qaeda network.
Richard Dowden, executive director of the Royal African Society, said the terror warnings did not seem credible and may have been issued by politicians worried by the "Bali factor".
Anybody planning a trip in the near future is advised by the Foreign Office to keep an eye on the latest information.
Its most recent update, issued in mid-April, said: "The situation in Iraq has increased the possibility of public disturbances in Morocco, as in other countries in the region; some of these could become unruly.
"Morocco is also one of a number of countries where there is an increased threat from international terrorism."
The targets in Friday's attacks included the Belgian consulate, the Safir Hotel, a Jewish community centre, a Jewish cemetery and a Spanish cultural centre and restaurant, Casa de Espana.
The British tourists who had been in the Safir Hotel have been moved to another hotel.
A Foreign Office spokeswoman said consular
staff had checked all the hospitals in Casablanca and no Britons had been found.
Moroccan Interior Minister Mustapha Sahel said the attacks "bear the hallmark of international terrorism", adding that 10 suicide bombers were among those killed.
The suspension of British flights to and from Kenya has been criticised by the East African country's government as an over-reaction.
A Kenyan minister has said the ban was based on a specific threat to British Airways flight to the capital Nairobi until the end of May.
Hundreds of British tourists were stranded by the action, prompting Kenya Airways to step in and offer to lay on extra flights.
"We are now working with the British High Commission in Nairobi to assist any
Britons who want to get home," said Kenya Airways spokeswoman Sally Peters.
The British High Commissioner to Kenya, Edward Clay, said everything is being done to help the stranded British tourists.
British holiday companies have cancelled all bookings to Kenya for the next seven days.
Richard Dowden said the Morocco attacks showed the UK Government had picked the wrong countries for its travel alerts.
After warnings were issued about the six East African countries, he said: "I don't find them credible, the idea that all these countries bunched together, covering a vast area could suddenly become a threat like this from absolutely nowhere is just not believable.
"The Kenyan one was believable because an attack had been made on a specific plane - the Israeli charter plane last November."
Mr Dowden said he would not think twice about going to any of the countries on the list - places which were trying to fight terrorism and need to see overseas visitors.