The Solomon Islands opposition leader, Manasseh Sogavare, says the former police commissioner Shane Castles should not be allowed to return.
Mr Sogavare declared Mr Castles a prohibited immigrant in 2006 while the Australian was still the police chief, and on leave in his country.
But the new government revoked the ban last week at the request of the Director of Public Prosecution Ronald Bei Talasasa.
And Mr Castles is now in the country to give evidence in court against a former immigration minister, Peter Shanel.
Mr Shanel was charged in relation to the illegal landing of a Papua New Guinea plane carrying fugitive Julian Moti to Munda in October 2006.
Mr Sogavare has told the Solomon Star paper that the government's action in lifting the ban is irresponsible and hypocritical.
He said his government declared Mr Castles a prohibited immigrant because of his misconduct in office and questionable appointment.
