"We here hear talk of the 'unbearable' number of asylum seekers, an attitude that is unfortunately fed by these salesmen" who are merely pandering to voters, Nunzio Galantino, secretary general of the Italian Bishops' Conference (CEI), said in an interview on Vatican Radio.
The head of the anti-immigration Northern League party, Matteo Salvini, was quick to lash out at the Roman Catholic Church, saying "those who defend this illegal invasion, which is ruining Italy, either don't understand or are making money" from the migrant arrivals.
Tempers have been fraying in recent weeks over the reception of migrants and would-be refugees in Italy, with Pope Francis intensifying his pleas for those fleeing war or persecution to be taken in - despite increasing anger over the numbers being rescued.
With the Italian coast guard reporting new operations daily, Salvini asked if those picked up at sea "will be taken to Brussels or the Vatican?"
The League insists those who urge Italy to save migrants should also shoulder the responsibility for looking after them.
Italy's anti-establishment Five Stars (M5S) party has also called for greater controls over asylum seekers and a "tightening up" of permits.
The CEI's head, Angelo Bagnasco, denounced "the indifference shown to the exodus of desperate people forced by poverty, war and persecution to take their chances elsewhere".
Over 1,500 migrants were rescued Monday from seven boats which had run into trouble off Libya, according to the Italian coast guard.
The UNHCR said last week that some 224,000 migrants have arrived in Europe via the Mediterranean since the start of the year - 98,000 in Italy and 124,000 in Greece - and over 2,100 people have died during the crossing.