Afghan Taliban leader Mullah Akhtar Mansour was seriously injured in a firefight following a heated argument at a meeting of militant commanders, officials said Wednesday, exposing deepening divisions within the fractious militant movement.

It was unclear if he survived the clash, which occurred just four months after Mansour was appointed Taliban supremo in a deeply acrimonious leadership succession.

Spain's Constitutional Court on Wednesday revoked a resolution passed by Catalonia's parliament that declared the start of a secession process in the wealthy northeastern region, Prime Minister Mariano Rajoy said.

"It was a unanimous decision," the conservative prime minister said during a speech.

Aid workers in war-torn South Sudan have reached one of the worst hit areas where thousands are feared dying of starvation, the United Nations said Tuesday, but warned conditions may yet worsen.

Two teams of aid workers reached the town of Leer in southern Unity state, the U.N. said, scene of some of the heaviest fighting, including the mass abduction and rape of women and children.

Slovakia said Wednesday it had mounted a legal challenge to the EU's plan to distribute 160,000 asylum-seekers among member-states under a quota system.

"The Slovak republic has officially filed a lawsuit against the Council of the European Union, to the highest court ... in Luxembourg," leftist Prime Minister Robert Fico said.

Belgian police on Wednesday held two people for questioning in connection with the Paris attacks, after carrying out a series of searches in their hunt for key suspects with links to the November 13 massacre.

"This morning five premises were searched in the Brussels region, concerning the ongoing federal investigation into the fugitive Mohamed Abrini and into Ahmed Dahmani who is currently detained in Turkey," the federal prosecutor said in a statement.

Cameroon troops killed around 100 Boko Haram Islamist fighters from Nigeria, freed almost 900 hostages and seized Islamic State (IS) flags last week, the defense ministry said Wednesday.

"A special clean-up operation from November 26 to 28" against Boko Haram fighters in the border area with Nigeria "neutralized more than 100 jihadists", Defense Minister Joseph Beti Assomo said in a statement broadcast on national radio.

A Vatican leaks scandal that was already rich in claims of sex, scheming and spying has widened to embroil Silvio Berlusconi and add allegations of blackmail and computer hacking to the mix.

Former prime minister Berlusconi denied late Tuesday that he had had any contact with Francesca Chaouqui, an ex-PR consultant to the Vatican who is one of five people, including two journalists, on trial over the leaking of classified Holy See documents.

Russia's Foreign Minister Sergei Lavrov said Wednesday he was willing to meet his Turkish counterpart this week for the two countries' first high-level face-to-face talks since Ankara shot down one of Moscow's warplanes.

Lavrov said Turkish Foreign Minister Mevlut Cavusoglu was "insisting" on holding talks on the sidelines of the OSCE Ministerial Council in Belgrade on Thursday and Friday.

Prime Minister David Cameron, who is negotiating with Britain's EU partners on its conditions of membership, is aiming for a deal at an EU summit in December, European Council President Donald Tusk has said.

"If he is ready to take this risk, I will be helpful. But then, it would be his risk," Tusk was quoted as saying in an interview with the Guardian and five other European newspapers published on Wednesday.

U.S. Secretary of State John Kerry on Wednesday urged NATO allies to intensify the fight against the Islamic State as Washington leads the military campaign against the extremist group.

"I called on every NATO ally to step up support in the fight against Daesh (IS), striking at the organization’s core in Syria and Iraq," Kerry said after a meeting of foreign ministers from the 28 NATO states in Brussels.