India Monday intensified measures to tackle any possible swine flu case from entering the country by beefing surveillance at border road posts, as five more people arriving from abroad were quarantined with suspected flu symptoms.

Health authorities have so far collected 15 samples of suspected flu cases, of which 12 have been found negative.'A total of 41,498 air passengers have been screened so far, and around 8,353 passengers were from affected countries. 172 doctors and 82 paramedics have been deployed to man 61 counters at 21 airports across the country,'

On the plan to intensify surveillance on border roads, he said: 'We are planning to introduce screening on road checkposts in Uttar Pradesh and Bihar. We have information that about 84 people from affected countries had come to India by road in the last one week. We are tracking them.' But he declined to name the countries the people had come from or their identities.

'As of today, five people are under observation. None of them is foreigner. They are all Indians. While three of them have been admitted to Delhi government hospitals, two are in Kochi,' the official said.

Among the three kept in isolation ward in a Delhi hospital, one had come from Germany and two from the US.'The samples of three passengers in Delhi have been sent to the National Institute of Communicable Diseases (New Delhi), and the test results are awaited while samples of Kochi passengers are awaited,' Chawdhry said.

He added that the two in Kochi had come from Dubai after visiting the US and Britain.'If the number of samples goes up, we will send samples to two other central government laboratories in Kolkata and Dibrugarh (in Assam) for tests,'.

Government would be able to get one million capsules of the anti-viral drug Tamiflu by Tuesday from Hyderabad-based Hetero drugs. Eight million more doses would be made available in a week's time, he added.

According to the World Health Organisation (WHO), 20 countries have reported 1,000 cases of swine flu so far. Mexico, the epicentre of the infection, has reported 590 confirmed human cases, including 25 deaths, the WHO said.

The 21 airports in the country where screening is being done are at Ahmedabad, Amritsar, Bangalore, Calicut, Chennai, Cochin, Coimbatore, Delhi, Varanasi, Goa, Hyderabad, Jaipur, Kolkata, Lucknow, Mangalore, Mumbai, Nagpur, Pune, Srinagar, Trichy and Tiruvananthapuram.