WARSAW Poland may hold a referendum on a European Union migration deal on the same day as elections set for the autumn, a deputy minister said on Monday, underscoring the ruling nationalist party's opposition to the EU deal in its campaign.

Under the deal, which aims to settle divisions that date back to the 2015 migrant crisis, each member of the 27-member EU would be responsible for admitting a set number of migrants but could make payments of around 20,000 euros per person to other states if they do not wish to host them.

However, Jaroslaw Kaczynski, leader of the ruling Law and Justice party (PiS), said on Thursday Poland would hold a referendum on the deal as it had already taken in 1.5-2 million Ukrainian refugees and it would be unfair to expect Warsaw to pay for declining to take in other migrants.

Eastern EU countries such as Poland and Hungary have in the past refused to admit migrants from the mainly Muslim Middle East and North Africa. PiS has been accused by human rights groups of stirring up xenophobia, which it denies.

Asked in an interview with private broadcaster Radio Wnet whether the referendum could be held on the same day as the parliamentary election, set for October or November, Deputy Foreign Minister Pawel Jablonski said this was possible.

"These types of joint votes have already taken place in the past and I think it would be a natural thing, also because of the costs," he said.

A United Surveys poll published by Dziennik Gazeta Prawna daily and RMF FM on Monday showed that half of Poles were in favour of a referendum, but half opposed the idea of twinning it with elections.

Donald Tusk, leader of the main liberal opposition party Civic Platform, told a rally in the city of Poznan on Friday that the referendum proposal was a sign of fear on the part of PiS amid public dissatisfaction over topics such as inflation or the country's strict abortion laws.

(Reporting by Alan Charlish and Pawel Florkiewicz, editing by Mark Heinrich)