Replying to a question in Rajya Sabha, Krishna said, "We have taken a position that no stapled paper attached to Indian passport is acceptable to us as visa."
He pointed out that some Indian nationals with a Chinese visa on a separate sheet of paper stapled to their passports are undertaking travel to China via Hong Kong.
"Such stapled visas are not considered valid for travel abroad by the government," he said.
He added, "The Indian immigration authorities have been sensitised to this possibility."
China had started the practice of issuing visas to people hailing from Jammu Kashmir on separate sheet of paper rather than passports, apparently to suggest that the state was disputed.
Krishna also said the government has taken up the matter with China on several occasions in the recent past.