In the aftermath of Pakistani-American terror suspect David Coleman Headley episode, India has revised its regulations pertaining to entry of foreign nationals holding long-term tourist visas.

In an advisory to its citizens, the US has said India has revised its regulations pertaining to the entry of foreign nationals holding long-term Indian tourist visas and various ports of entry in India have already started enforcing the revised regulations.

"Americans with five-or ten-year tourist visas will no longer be allowed to enter India within two months of their last departure from India if their last visit was longer than ninety days or if they have stayed longer than 180 days during the past year," the advisory on the embassy website said.

The revision of the regulations comes in wake of the arrest of Headley and Pakistani-Canadian Tahawwur Rana Hussain by FBI on charges of plotting terror attacks in India. Both Headley and Rana were issued multi-entry visas by India without proper security clearances.

The US advisory also said these restrictions will be enforced whether or not the tourists passport has been stamped to indicate that return is not allowed within two months.

However, the changes will not affect Americans with other types of visas such as tourists with short-term visas, and those who have not stayed in India for the stipulated time period.

Tourists who wish to return within this two-month period can apply for special permission through any Indian High Commission or Consulate, the US embassy said.

It also asked the applicants to clearly state their purpose of travel and that they are not traveling to India for business, employment, study, or research.

There are no standard guidelines for approving these applications but they will only be approved in emergent situations like a death or illness in the family or the need to travel through India en route to another country, the advisory by the US Embassy said.

Tourists, who are given permission to return within two months, will be required to register with the Foreigners Regional Registration Office (FRRO) within fourteen days of arriving in India.

The updated information also notes that tourist visas are intended for recreation, sightseeing, and short-term visits with family and friends and other travelers should apply for an appropriate visa based on their purpose of travel, whether business, employment, medical, or other.