NEW DELHIinfo-icon: Security experts in Indiainfo-icon say it is a common tactic for countries to tap the employees of foreign governments to get access to confidential information, but catching a double agent is a work of vigilance.The most recent of such cases is that of Madhuri Gupta, an Indian diplomat who was sentenced to three years by an Indian courtinfo-icon on Sunday for spying for Pakistaninfo-icon.

On Friday a court found Gupta guilty of "spying and wrongful communication of information" while posted to the Indian embassy in Islamabad, according to news reports. Gupta, 61, is out on bail and plans to appeal the sentence.

Gupta, a low-ranking diplomat, was stationed at the Indian High Commission in Pakistan as second secretary (press and information). She was arrested in 2010 for allegedly passing information to Pakistan's intelligence unit, ISI or the Inter-Services Intelligence, a charge that she has admitted.

According to security experts, Gupta was allegedly in a relationship with a Pakistani man to whom she passed on classified information."It was a reverse honey trap," said V. Balachandran, a former special secretary in the cabinet secretariat. "This is an old Stasi tactic and she was caught in that."Confidential information 

The Stasi was East Germanyinfo-icon's official security service when that country was divided in two. It was common practice for the Stasi to have young, handsome East German officers pretend to be West German to meet single West German women posted at embassies and woo them to access confidential information, Balachandran said.

"The good thing is our counterintelligence caught on to it," he said. "Keeping a watch on your own people is a difficult thing, especially in hostile countries like Islamabad. Despite that they've been able to do this and shows that they are quite alert."

While spying or espionage is common in all countries, it is not common to be caught, experts agree."Sometimes these things come to light and there are times that they don't," said A.S. Dulat, former special director of India's Intelligence Bureau who also headed the researchinfo-icon and analysisinfo-icon wing. "Not everything gets known. If it does, espionage will come to an end. It's the luck of the draw."

Money, sexual favors or loneliness can drive people to reveal their country's secrets to an enemy nation, Balachandran said."That's why as a security precaution we always say that single people shouldn't be posted to such embassies, as without a family support network they can get very lonely" and be easy prey, he said.

The extent of the damage, experts agree, depends on what information is leaked.

In the so-called Naval Warinfo-icon Room leak, officers of the Indian Navy allegedly stole more than 7,000 pages of documents on India's maritime preparedness and plans for the next 20 years and leaked them to armsdealers and middlemen.

"That was a very damaging case," Balachandran said. "And these things happen because of our own failure to notice" the warning signs, he said.Nuclear-armed arch-rivals India and Pakistan frequently accuse each other of sending spies to their countries and have on several occasions expelled diplomats after allegations of espionage.