Kenya rebuked Britain, the United States, France and Australia on Thursday for issuing warnings about travel to the east African country, while hoteliers said at least 400 tourists had checked out of hotels along the Indian Ocean coast.
Kenya called the alerts "unfriendly", saying they would increase panic and play into the hands of those behind the gun and grenade assaults that have hit the capital Nairobi and the coastal resort of Mombasa.
Explosions in both cities on the weekend of May 3-4, one of them at a luxury seaside hotel, killed seven people, although no one was hurt in the hotel attack. Kenya blames the blasts on the al Qaeda-linked Somali group al Shabaab.
The Islamist movement killed at least 67 people in a gun and grenade raid on a Nairobi shopping mall last September, claiming it as revenge for attacks on its fighters by Kenyan troops in Somalia.
The warnings and departures by tourists from hotels along the popular coast are further harming Kenya's tourism sector, which President Uhuru Kenyatta has said is "on its knees" following the deadly attacks.
Britain told its citizens to avoid Mombasa, and the United States cited hotels, nightclubs and malls as possible targets.
Australia urged its citizens to reconsider trips to Nairobi and Mombasa "due to the high threat of terrorist attack and high level of crime". France warned of an elevated risk in Kenya, especially in those cities.
Karanja Kibicho, principal secretary at Kenya's foreign affairs department, said the advisories "are obviously unfriendly acts", and assured tourists they were safe while visiting the country.
Kenyan authorities say they have beefed up security after the attacks, and deported foreigners without proper documents.
"The threats are perpetual, we are at war. But we have not received any specific threat on the hotels," said Interior Ministry spokesman Mwenda Njoka.
But tourists were still leaving. At least 400 checked out of their hotels, heeding the travel advisories, according to Sam Ikwaye of the Kenya Association of Hotelkeepers and Caterers. "We fear many more will leave," Ikwaye told Reuters.
Planes had been chartered to fly out the departing tourists.
Augustine Conall, a British national, told journalists at the Moi International airport in Mombasa, he had cut short his three-week holiday by a week, worried that his insurance would no longer be valid.
"Our families are also worried and are calling us and telling us to go back," he said.
Another Briton, Matilda Evan, said: "Six days of my holiday have gone to waste just like that. But again, when your government tells you to leave for security reasons, what else can do you do?"
She was in Kenya for a third time, travelling with a group of eight female friends. All were going back.
Tourist arrivals in Kenya fell 15.8 percent to 1.49 million last year as security worries kept visitors away. Britain is the country's biggest source of visitors.
Tourism is one of Kenya's biggest foreign exchange earners, employing 150,000 people. Travel agents said they hoped other destinations in the great Rift Valley and around Mount Kenya would still attract visitors.
Western diplomats have privately said Kenyan security forces - which receive aid and training from the United States, Britain and Israel among others - are weakened by inter-agency rivalries that hamper intelligence work.