New Delhi, Apr 8 (IANS): Delhi Police heaved a big sigh of relief Sunday as Pakistani President Asif Ali Zardari left the capital after a two-hour visit that was a security nightmare.

Zardari's stay in the capital was a challenging task for the senior Delhi Police officers overseeing security arrangements of a man who is a highly guarded person in Pakistan and faces terror threats, said a officer who spoke on condition of anonymity.

"The city was turned into a fortress since Sunday morning with the deployment of more than 2,000 police personnel,including traffic police, all across the central Delhi and along the routes taken by Zardari's cavalcade," said the officer.

The route taken by Zardari's cavalcade between Palam airport and the prime minister's 7, Race Course Road residence was cordoned off till 2 p.m. Sunday.

As soon as Zardari, accompanied by his son Bilawal, Interior Minister Rehman Malik and a large delegation in two planeloads landed at Palam airport, vehicular movement for the public was restricted.

"The restriction was halted till Zardari's return from 7,RCR to the Palam airport," the officer added.

He said that more than 100 police personnel armed with sophisticated weapons were deployed on highrise buildings along the route.

A number of Police Control Room vans were stationed along the route and in other parts of central Delhi, the officer said.

Zardari flew from the capital to Jaipur and thence to Ajmer.