Vanuatu's first president and the country's chiefly council have also criticized the programme through which thousands of people have purchased citizenship, making them eligible to acquire passports.
Last month, the International Monetary Fund urged Vanuatu to reduce its reliance on the programme for which it forecast fewer applications.
Opposition leader Ishmael Kalsakau said the government was putting itself at risk as revenue from the scheme would dry up.
"If the government is really serious about passports - do it the right way, and that is through the diplomatic missions that we have," Mr Kalsakau said.
The programme is also to blame for the recent deportation of six Chinese nationals, four of whom held Vanuatu passports, he said.
"If they [the government] continue with what's going on at the moment, it's always going to be open to questions when you have suspicious people coming in because these people don't have access to the right kind of checks that you would normally get."