German Interior Minister Horst Seehofer on Saturday said he remained optimistic about completing a deal on migrants with Italy despite pushback from Italian Deputy Prime Minister Matteo Salvini.

Salvini on Friday denied having reached a deal to take back migrants who had already applied for asylum in Italy, saying he wanted more concessions from Berlin.

Seehofer had announced on Thursday that he had secured an accord with Italy over the issue in line with similar deals negotiated with Greece and Spain. 

"I'm sticking to what I said: We will get it done," Seehofer said during a party congress of his Bavarian conservative party.

Seehofer's push for tougher immigration policies nearly led to the collapse of the German coalition government earlier this year. Since then, Germany has pressed southern EU states to take back asylum seekers previously registered in these countries.

Salvini cautioned on Friday that he wasn't ready to put his name to a deal with Germany, although he said German officials had assured him that they would accept a bona fide asylum seeker from Italy for every migrant that Germany returned to Italy.

He said he wanted "to see the availability and openness" of Germany on two other issues - a revision of both the EU's Dublin Treaty on how Europe handles asylum requests, and of the EU's Sophia naval mission which is patrolling the Mediterranean.

Seehofer did not address those issues in his remarks.

Italy has become the main route into Europe for hundreds of thousands of asylum seekers arriving by sea since the other main route from Turkey to Greece was largely shut in 2016. However, numbers have fallen sharply over the past 12 months.