TOKYO, JAPAN - Japan Tuesday tightened visa rules for citizens of Mexico, the centre of the global swine flu outbreak, and told its own nationals there to consider leaving the country.

Japan, which earlier stepped up health controls at its airports, also booked 500 hotel rooms near Tokyo's Narita International Airport in case it needs them to quarantine infected travellers, reports said.

Tokyo took the new steps as Mexico said the number of probable deaths from the virus had risen to 152 and the World Health Organisation (WHO) raised its alert to signal a 'significant increase in risk of a pandemic.'

Prime Minister Taro Aso said the 'government will do its best to secure the people's safety by conducting border controls, disclosing information to the public and maintaining close coordination with the international community.'

Foreign Minister Hirofumi Nakasone said Japan's embassy in Mexico would from Tuesday suspend a visa waiver programme - meaning Mexicans no longer get Japanese visas on arrival but have to apply in advance, an official said. 'This is part of our effort to stop the virus from entering our country,' the foreign ministry official told AFP.

Nakasone had also 'asked Japanese citizens in Mexico to consider their early departure if possible as there could be a problem with leaving the country in the future,' said the official, who declined to be named.

Mexico's embassy in Tokyo cancelled a Mexican music festival scheduled for early May because of difficulties in sending musicians, organisers said.

Health Minister Yoichi Masuzoe, meanwhile, asked Japanese people 'to consider avoiding trips to Mexico and other affected countries.'

Jiji Press reported that Japan's health ministry had booked 500 rooms near Narita airport and was also in talks with hotel operators near Kansai, Chubu and Fukuoka airports to secure more rooms to quarantine passengers.

If the WHO further heightens its alert level, Japan would quarantine arrivals suspected of having the disease, as well as those who accompany them and the flight attendants, for 10 days of tests, the report said.

The Tokyo metropolitan government has released anti-flu drugs Tamiflu and Relenza for 8,000 potential patients to major hospitals in the capital in case of a future outbreak of swine flu, officials said.

Several Japanese companies, including Honda Motor Co, said they would cancel business trips to Mexico and the United States for now, while beverage maker Suntory Holdings Ltd. said it temporarily closed a Mexico City liquor plant.

Japanese restaurant chain Matsuya, meanwhile, took dishes with Mexican pork off the menu, but the government has said it has no plan to ban pork imports from Mexico or the United States.