Italy's interior minister Angelino Alfano has said a time limit must be put on the humanitarian search-and-rescue operation that has saved some 63,000 migrants since last year. Last weekend alone, more than 2,000 people came ashore in southern Italian ports, under the auspices of the country's Mare Nostrum (Our Sea) operation.

"With regard to immigration, Italy has once again shown itself to be a world champion in hospitality," Alfano told a press conference in Rome on Friday. But he added that, if the European Union and its border management agency did not take over the operation, "the Italian government will have to take decisions on the matter".

The previous government, headed by Enrico Letta, launched Mare Nostrum following the biggest single disaster in the recent history of irregular migration in the Mediterranean. Last October, 368 people – most of them Eritreans – died after a fire on board their within sight of land off the Italian island of Lampedusa.

Alfano, leader of the New Centre-Right (NCD) – the junior partner in the present coalition government – said the operation should not be allowed to reach its second anniversary. It was the latest indication of tension within Matteo Renzi's left-right coalition on the issue of immigration in just a few days.

Earlier this week, Alfano announced a crackdown on beach pedlars, most of whom in Italy are immigrants. In doing so, he caused a stir by describing them as "Vu cumpra", a derogatory term imitating the mispronunciation of "Vuoi comprare?" (Do you want to buy?).

In a clear rebuke to Alfano, the prime minister said afterwards that he would not have used the term. According to interior ministry figures, 116,944 migrants arrived by sea in Italy in the 12 months to 31 July, of whom 62,982 were rescued in Operation Mare Nostrum.