French President Emmanuel Macron called on Libyan authorities Monday to stop holding transiting refugees in detention camps and said buildings of the United Nations' refugee agency in Libya were attacked earlier in the day.

Macron did not elaborate on the attack he said was carried out on buildings of the U.N. High Commissioner for Refugees. He said Libya should end the "confinement" of refugees and house in safe places those who reach the North African country.

Libya has become a major conduit for African migrants and refugees hoping to reach Europe by crossing the Mediterranean Sea. An airstrike on a detention center near the Libyan capital killed more than 50 migrants and wounded dozens of others earlier this month.

Macron met with U.N. High Commissioner for Refugees Filippo Grandi and the director general of the International Organization for Migration on Monday, after European ministers in Paris tried to find agreement on dealing with Europe-bound migrants who use Libya as a stepping stone.

The European Union has spent hundreds of millions of euros to equip and train Libya's coast guard and to improve the conditions of the detention centers. Under a deal with the EU, Libyan vessels apprehend refugees and migrants setting out from the coast and take them back.

Macron announced that eight countries had formally signed on to a French-German initiative to cooperate in a burden-sharing mechanism and 14 assented to it. Southern European countries like Italy and Greece have complained for years that they shoulder a disproportionate responsibility for arriving migrants.

"Europe isn't a la carte when it comes to solidarity," Macron said, with countries saying they don't want a Europe that shares burdens but are in favor of unity "when it's about receiving structural funds."

Absent from the closed-door meeting of EU interior and foreign ministers was Italy's populist, anti-migrant interior minister, Matteo Salvini. He tweeted strong disagreement Sunday with letting France and Germany determine the bloc's refugee policy while nations like Italy are on the front line.

"We intend to make ourselves respected," Salvini declared in another tweet.

Without naming Italy, Macron regretted the absence of some countries from the table, saying that "we gain nothing by non-cooperation."

However, he reiterated the law of the sea by which boats must be able to enter the surest and closest port, which for vessels coming from Libya typically is Italy.

Salvini has barred private aid ships that rescue migrants from entering Italy's ports, forcing NGOs to find another country willing to allow their rescue boats to dock and bartering among nations to divide up the migrants onboard.

U.N. High Commissioner Grandi said he was encouraged by the progress in finding a method for sharing the work of housing asylum-seekers and processing their applications.

Last month, Grandi and International Organization for Migration Director General Antonio Vitorino lamented that the EU had no predictable strategy for providing rescue boats with safe harbor and sharing newly arrived migrants.

The number of migrant crossings on the central Mediterranean route that leads to Italy has diminished drastically since 2015 and 2016.

"We no longer are living an arrival crisis .... We live a crisis of deaths," Vitorino said.

According to the IOM, up to June 19, there were 2,252 arrivals in Italy and 1,151 in Malta, while at least 343 people died at sea.

German Foreign Minister Heiko Maas voiced hope earlier in the day that a solution was on the horizon.

"The haggling about emergency rescue in the Mediterranean must finally end," German Foreign Minister Heiko Maas said after the ministerial meeting. "It is really necessary that we manage to put together a coalition of those who are prepared to help, and I think we came a step closer to that today."

The UNHCR and IOM chiefs joined Macron in stressing the need for rescue help from NGOs, which Italy has denounced, claiming they help traffickers.

On Sunday, the SOS Mediterranee, a French charity, partnering with Doctors Without Borders, announced it has returned to the sea with a new boat to save migrants, seven months after the flag was pulled from its original ship, Aquarius. The Norwegian-flagged Ocean Viking is heading to the Mediterranean with a 31-member crew, the group said.

Salvini wasted no time in warning SOS Mediterranee that Italy was not about to bend on its policy of keeping rescue ships at bay, tweeting Monday, "if someone is thinking about helping smugglers or breaking laws, be careful because we won't be standing still."

The Aquarius, SOS Mediterranee's original rescue ship, ended its operations last fall after Panama revoked its flag and Italian prosecutors ordered the vessel seized, accusing Doctors Without Borders of illegally disposing of tons of contaminated and medical waste. The organization says the Aquarius assisted 30,000 migrants since 2016.

Monday's meeting follows a gathering of EU interior ministers on the issue of rescuing migrants last week in Helsinki, Finland. Salvini hailed progress there, saying other ministers shared Italy's position of revamping Mediterranean search and rescue rules with the aim of preventing immigration abuse.