The Indian city of Ahmedabad is restricting public gatherings to contain a swine flu outbreak.
Officials in the Gujarat city said 231 people had died of the flu in the state since January, with more than 3,500 cases detected so far.
On Monday, Gujarat's junior health minister and the assembly speaker were diagnosed with the virus.
India's swine flu outbreak has killed 875 people nationwide since it took hold in mid-December.
The number of cases has crossed 15,000 in what is the deadliest outbreak of the H1N1 virus since 2010.
Federal Health Minister JP Nadda told parliament on Tuesday that swine flu was becoming a "matter of great concern" although there had been "no mutation of the virus".
What is swine flu?
- A respiratory disease caused by a strain of the influenza type A virus known as H1N1, which first appeared in Mexico in 2009
- Originated in pigs, but is now a human disease spread by coughing and sneezing
- Symptoms similar to those produced by standard, seasonal flu - fever, cough, sore throat, body aches and chills
- Vulnerable groups include pregnant women, children under five, the over-65s and those with serious medical conditions
Gujarat is the home state of Prime Minister Narendra Modi and one of the worst affected states. It has the second-highest flu death toll after neighbouring Rajasthan, where the disease has claimed 225 lives.
Fifty people have died of the flu in Ahmedabad, the largest city in Gujarat, since the beginning of the year.
The administrator of Ahmedabad said on Tuesday that anyone wanting to hold a public gathering would have seek prior permission and would be required to provide masks, hand sanitisers and water.
Only weddings and funerals would be exempt, senior city administrator Rajkumar Beniwal told the AFP news agency.
The BBC Hindi's Ankur Jain in Ahmedabad says a number of events, including a yearly marathon and music concerts, have now been called off.
Although there is no panic in the city, our correspondent says some offices have told their employees to wear masks at work, and schools and colleges are telling students suffering from a cold to stay away until they get well.
Authorities have been blamed for failing to tackle the situation, but Gujarat's health minister said there was "no need for declaring the swine flu outbreak as [an] epidemic as the situation is under control".
Health authorities across India have launched TV and radio campaigns to tell people about precautions they can take to avoid the flu.
The virus has killed nearly 4,000 people in India since 2009.