A "giant refugee city" should be built on the Libyan coast to process asylum claims before they reach Europe, the anti-immigration Prime Minister of Hungary has suggested.

Victor Orban repeated the idea after a summit of European Union leaders in Vienna, saying the EU's external borders must be under "total control". While he spoke a bomb blast rocked the Hungarian capital Budapest, injuring two police officers a week before a controversial referendum on the EU's plans for mandatory relocation of refugees and migrants.

Libya is a key gateway for those fleeing poverty and war in Africa and seeking to travel to Europe. The International Organisation for Migration (IOM) estimates there are more than 264,000 refugees and migrants currently in the north African country.

Orban's right-wing government has closed its borders to migrants and refugees fleeing war in Syria and has proposed a Christian-only policy towards accepting refugees. He has refused to accept Hungary's quota of refugees and migrants under the EU's forced relocation scheme and Hungarians are expected to back the government in a referendum on October 2.

The Hungarian government has refused to accept Muslim refugees because they said they want to "preserve the Christian values" of their nation.

Earlier in September the government established an office on the persecution of Christians, the first of its kind in Europe. The office's three million euro budget will mainly focus on humanitarian work in the Middle East but also on "forms of discrimination and persecution of Christians all over the world".

Zoltán Balog, the Hungarian minister for human capacities, said: "It is therefore to be expected that we will keep a vigilant eye on the more subtle forms of persecutions within European borders."

He said the Hungarian government considers the office of "utmost importance" to protect Christians' "untenable situation" and raise awareness of their plight.

"Today, Christianity has become the most persecuted religion, where out of five people killed out of religious reasons, four of them are Christians," Balog told Catholic News Agency (CNA).

"In 81 countries around the world Christians are persecuted and 200 million Christians live in areas where they are discriminated against. Millions of Christian lives are threatened by followers of radical religious ideologies."