All of the UK's major tour operators have suspended holidays to Kenya for the next two days, the Federation of Tour Operators has said.
UK travel firms have cancelled holidays to Kenya until Monday, the Federation of Tour Operators (FTO) has announced.
Operators began cancelling flights following Foreign Office advice that people should only take essential journeys to the East African country.
An estimated 500 people will be hit by the move which comes amid continuing Foreign Office advice against all but essential travel to the country.
More than 300 people have been killed in Kenya and at least 70,000 driven from their homes since Sunday.
All major UK tour operators had already suspended holidays until Saturday.
The crisis flared after claims of vote rigging in the presidential election.
The FTO said Monday was a major return-home day for UK tourists in Kenya and holiday airlines will send planes to bring people back.
The Federation of Tour Operators (FTO) is also assessing the need to make alternative travel arrangements for 7,000 Britons who are already on holiday in Kenya.
The east African country has been gripped by violent clashes in the wake of the disputed presidential election.
The Foreign Office had advised people to avoid all but essential travel to certain parts of Kenya following violence that erupted on 27 December.
The Foreign Office has urged anyone in affected areas, including Mombasa, Eldoret and Kisumu, to remain indoors and to "exercise extreme caution".
But on Wednesday night this advice was extended to the entire country.
Announcing the latest ban, FTO spokesman Graham Lancaster said: "Foreign Office advice against all but essential travel to Kenya is still in place and we thought it best to extend the cancellation dates."
It also recommended that anyone already in Kenya should "exercise extreme caution".
He added: "About 500 people are affected by the cancellation of trips on Sunday and Monday. The FTO will be deciding over the weekend on holiday arrangements for the days after Monday."
The Foreign Office said on its travel advice website: "We advise against all but essential travel to Kenya.
Volatile
"There is uncertainty about the security and political situation in the country especially in light of the massed rallies planned for 3 January and continued unrest linked to the disputed presidential election result.
British Airways, Virgin Atlantic and Kenya Airways are continuing UK-Kenya scheduled services as normal.
The violence has been mainly confined to urban areas, well-away from the country's popular beach resorts and safari parks.
It said travellers should check the site for up-dates.
But many tourists have to travel through Mombasa or Nairobi to reach their destinations.
But Frances Tuke of the Association of British Travel Agents (Abta) said people holidaying in Kenya should be safe despite the unrest, as long as they were far from the trouble zones and were careful.
An increasingly popular tourist destination, about 200,000 Britons visited Kenya last year, with numbers peaking in late January and February.
She said: "If people are out there on safari it's well away from the problem spots and so their holidays are going on as normal.
Cancellations also mean UK holiday companies having to refund passengers who choose not to take or cannot be accommodated on alternative holidays.
"Down in the beach resort most people are staying in their hotels and they are being advised to do that and going ahead with their holidays with extreme caution."
The Foreign Office says on its travel advice website that the situation "remains volatile".
She said most tour operators were offering holidaymakers whose trips had been cancelled either a later date to travel, an alternative holiday or a full refund.
"There are reports that daily mass gatherings are being planned for Nairobi and other urban areas. Such gatherings could potentially turn violent," it adds.
But those who decided to cancel their trips themselves before this latest Foreign Office advice were unlikely to be compensated by their tour operator, she added.
She advised those with a holiday booked after Saturday to contact their travel organiser and await further advice from the Foreign Office.
She also warned against cancelling in a panic as people could risk losing out financially.
Long-haul specialist Kuoni said the 209 people on the firm's holidays in the country were all safe and well and none had asked to come home.
It also said people due to travel within the next 48 hours would be offered alternative holidays or refunds.
A Kuoni spokesman said: "Should we not be able to find a suitable alternative holiday, then free-of-charge cancellation will be allowed."
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