The Union health secretary on Wednesday said "it is a distinct possibility" that some people in the country have contracted bird flu, a news agency reported.
According to official sources, 12 people have been tested positive in Maharashtra.
Earlier, bird flu was confirmed in two people who were under observation in Navapur in Maharashtra.
The samples of some of those quarantined tested positive for bird flu, according to health officials.
The government had ordered two new sophisticated testing procedures which will shorten the time taken to detect the virus in both human beings and birds.
PK Hota, the top civil servant in the federal health ministry, said tests on nine people hospitalised with flu-like symptoms were still being analysed.
The results were expected on Thursday.
"We do not rule out the possibility of humans being affected, and it is a distinct possibility," he was quoted as saying by a news agency.