Tunisian police have arrested a Libyan "terrorist" as he was trying to enter the south of the country with a "quantity of explosives," the interior ministry said on Thursday.

"The anti-terrorism task force with the help of units from the national guard arrested on Wednesday, May 8 a Libyan trying to enter with a quantity of explosives... The arrest took place after this terrorist was closely followed," it said.

Press reports warned Thursday that Tunisia was "at war with international terrorism" after the government revealed that jihadists being pursued by the army have ties to al-Qaida and the Islamist rebellion in Mali.

French-language daily Le Temps raised fears of "a spiral of deadly violence similar to the one that ravaged Algeria" during its so-called black decade of civil war in the 1990s.

Gunmen on a motorbike shot dead a police officer in south Yemen on Thursday, a security official said, a day after three senior air force pilots were killed in a similar Qaida-style attack.

"Two gunmen on a motorbike intercepted the police officer, a member of the political security services," in Huta, the provincial capital of Lahij, said the official.

Israel has warned the United States that Russia plans to sell sophisticated missile systems to Syria that would complicate any foreign intervention there, the Wall Street Journal reported.

The Journal reported late Wednesday that Israel had provided information to Washington about the imminent sale to Syria of Russian S-300 missile batteries, advanced ground-to-air weapons that can take out aircraft or guided missiles.

U.S. Secretary of State John Kerry insisted Thursday Syrian President Bashar Assad will have to step down as part of any political solution in Syria, as he held a third day of talks on the bloody conflict.

Speaking as he met Jordanian Foreign Minister Nasser Judeh, Kerry said all sides were working to "effect a transition government by mutual consent of both sides, which clearly means that in our judgment President Assad will not be a component of that transitional government."

The powerful jihadist group Al-Nusra Front has denied that its chief Abu Mohammed al-Jawlani was wounded in fighting near the Syrian capital of Damascus.

"Dear brothers, please note that what is being reported by some channels about the injury to Sheikh al-Jawlani in Damascus is not true, thank God," Nusra leader Al-Ghareeb al-Muhajir al-Qahtani said in a tweet late on Wednesday.

Israeli plans to build 300 new homes in a West Bank settlement near Ramallah prove that Israel is trying to "sabotage" U.S. efforts to revive peace talks, a top Palestinian official said on Thursday.

"We condemn this new decision which is proof that the Israeli government wants to sabotage and ruin the U.S. administration's efforts to revive the peace process," Palestinian negotiator Saeb Erakat told Agence France Presse.

Coptic Orthodox leader Tawadros II arrives in Rome on Thursday for a historic four-day visit to meet Pope Francis -- a sign of growing rapprochement between the Vatican and the Orthodox world.

The meeting on Friday will be the first between an Egyptian patriarch of Alexandria and a head of the Roman Catholic Church since 1973 when pope Paul VI met with Tawadros' predecessor Shenouda III.

Influential Muslim cleric Yusuf al-Qaradawi on Wednesday started his first visit to the Hamas-ruled Gaza Strip, crossing into the Palestinian territory at Rafah, on the border with Egypt.

An Agence France Presse photographer said Egyptian-born Qaradawi, who is a citizen of Qatar and close to the Muslim Brotherhood, arrived in the territory shortly after 9:30 pm (1830 GMT).

The leader of the powerful jihadist rebel force, Al-Nusra Front, was wounded by army bombing near the Syrian capital on Wednesday, a watchdog said.

Abu Mohammed al-Jawlani was wounded with other members of his group in southern Damascus province, the Syrian Observatory for Human Rights said, citing militants in the area.