Taking a tough stand, government on Tuesday invoked ESMA against employees who threatened to go on strike at Delhi airport and positioned 479 Air Force personnel at 21 airports across the country to deal with any contingency in the wake of the proposed agitation.

The Airport Authority Employees Joint Forum announced it will launch an indefinite 'non-cooperation movement' from midnight of Tuesday following government's rejection of their demand not to close Bangalore and Hyderabad airports.

"Delhi government has invoked Essential Services Maintenance Act at the Indira Gandhi International airport in New Delhi. It is already in operation," K N Srivastava, Joint Secretary Civil Aviation Ministry, said.

"I hope the unions know about large number of directives issued by Delhi High Court. I hope the unions remember these. We hope we will be able to control the situation and expect normal air services tomorrow," he said adding the management and the unions are still discussing the matter.

Government is also contemplating invoking a 1984 law, which empowers officers of the Bureau of Civil Aviation Security (BCAS) to arrest those who sabotage functioning of fire services, power and water supply and endanger safety and security of the airport.

"This law can be imposed," he cautioned.

Meanwhile, the Air Force moved 479 personnel to 21 airports, which include major airfields in New Delhi, Mumbai, Hyderabad, Chennai, Kolkata and Bangalore to deal with the situation.