Britain on Thursday said it was chartering flights from Tokyo to Hong Kong for its nationals trying to leave Japan as foreigners fleeing the country's nuclear crisis filled up commercial flights.
The move came a day after Britain advised its nationals to consider leaving Tokyo and northeast Japan following the earthquake, tsunami and subsequent explosions at the Fukushima nuclear facility.
"The UK government is chartering flights from Tokyo to Hong Kong to supplement commercially available options for those wishing to leave Japan," the Foreign Office said in a statement.
"The first option for leaving Japan should remain commercial routes."
Britons and their families directly affected by the natural disasters will not be charged for the charter flights and London will also pay for their onward travel to Britain, the Foreign Office said.
For those not directly affected, there will be a charge of £600 (690 euros, $960) per person for the Hong Kong flights, it added. Foreign Office staff will be available to help with onward bookings.
The United States has also chartered aircraft to take Americans out of the country and France has assigned two government planes to pull its people out.
British officials have stressed there is "no real human health issue" but concerns over the developing situation at the Fukushima site prompted London to update its travel advice.
London has also advised Britons to stay outside an 80-kilometre (50-mile) radius of the power station.
Chinook helicopters on Thursday dumped tonnes of water on the stricken nuclear plant in a desperate effort to cool reactors crippled by the earthquake and tsunami, which pulverised the northeast coast and left thousands dead.