Kolkata: The two Chinese nationals arrested earlier this week from the Bagdogra airport in West Bengal appear to be "tough spies on a specific mission", Indian intelligence officials said.
Until late Friday, the two have not broken up and coughed out anything despite persistent questioning, the officials said.
"Both pretend not to understand our questions. We are under orders not to use third degree, so they are getting away, but we have to find a way to break them," one intelligence official added.
What that currently worries Indian intelligence is the recovery of two forged Aadhaar cards with Uttar Pradesh addresses.
"The Aadhar card seems to be turning into a joke. Looks like anybody can procure it," the official said, adding: " There must be a support network in India to back up these Chinese agents with documentation, ticketing and much else."
Police in Bagdogra near Siliguri had earlier said that the two Chinese were arrested on Tuesday for travelling without any documents and booked for illegal trespass.
The Chinese nationals were identified by the police as Nav Jang Jung (39) and Kai Leng (42).
These could as well be fake names.
They appeared to be on their way to Tirupati in Andhra Pradesh when they were arrested.
"Tirupati or somewhere else," seems to be the key question bothering Indian intelligence now.
The two men were first taken under detention by the Central Industrial Security Force (CISF) which manages security at airports.
CISF officials had spotted their "suspicious movements" and handed them over to state police.
It was reported that one of the arrested Chinese nationals was carrying a passport but without any visa.
The otherperson was not able to produce any valid document, the police said.
By the look of it, the documentation provided to the two by their handlers appears to be shoddy and non-professional -- why should a Chinese carry the passport of his own country and an Indian Aadhar card is an obvious question.
"May be the passport is for protection during entry through the border after which they would throw it away and use the Indian Aadhar to melt into the Indian milieu. But why would they have Chinese names on Aadhar pointing to possible forgery or availability of Indian Aadhar through corrupt means," says a retired Intelligence Bureau official.
"That would automatically raise suspicion when the Aadhar is checked for identity proof at airports."
He said it should also be examined whether these Chinese had the benefit of some covert Pakistani network working in India to support ISI agents and terrorists.