Syria must grant unrestricted access to a U.N. investigation team following France's announcement that it has proof that President Bashar Assad's regime is using sarin gas in the country's civil war, Britain insisted Tuesday.

British Foreign Secretary William Hague said France's revelation that the regime was using the deadly nerve agent showed "the scale of the atrocities...is becoming ever clearer".

Tunisian police detained a Ukrainian topless activist in the capital Tunis before expelling her from the North African country on Tuesday, a leader of the women's protest movement Femen said.

"Some men entered her hotel room, ordered her to take her belongings and drove to the police... She was deported and is now on a plane to Kiev. Her passport has been given to the pilot," Femen's leader in Paris, Inna Shevchenko, told Agence France Presse on the phone.

Turkish Prime Minister Recep Tayyip Erdogan, facing unprecedented popular protests at home, charged on Tuesday that Syrian President Bashar Assad has committed atrocities worse than those attributed to his notorious father.

"Assad has surpassed his father in crimes and massacres, and it is not possible to forgive that. He will have to pay the price sooner or later," Erdogan said during a speech in Algeria, which he is visiting on a four-day tour of North Africa.

U.N. Secretary General Ban Ki-moon on Tuesday called a new report on growing atrocities in Syria's civil war "sickening and staggering", his spokesman said.

A U.N. panel investigating human rights abuses said there was "reasonable grounds" to believe that chemical weapons had been used by President Bashar Assad's forces and opposition rebels.

The International Federation of Red Cross and Red Crescent Societies appealed on Tuesday for more than $75 million to help hundreds of thousands of Syrian refugees in the region.

The IFRC "revised its existing emergency appeals from almost 37 million Swiss francs ($39 million/29.8 million euros) to 71.5 million Swiss ($75.35 million)" to help refugees in Jordan, Iraq, Lebanon and Turkey, a statement said.

French Foreign Minister Laurent Fabius said Tuesday that Paris had solid proof that President Bashar Assad's regime was using sarin gas in the Syrian conflict, adding "all options" are on the table.

"We have no doubt that the gas is being used..the laboratory tests are clear," he said on television after French laboratory tests on blood and hair samples from Syria pointed to the use of sarin gas.

The Turkish army returned fire after shots were fired at military targets from across the border with Syria, the military said in a statement Tuesday.

"A group on the Syrian side of the border fired 60 shots at an armored personnel carrier and tactical vehicles... which was reciprocated in kind" late on Monday, it said, adding that there was no damage or casualties.

Kuwait said on Tuesday that barring foreigners from attending public hospitals in the mornings was aimed at resolving the problem of "overcrowding" at such health facilities.

Since Sunday the health ministry in the oil-rich Gulf state began implementing the measure, described by activists as racist, at the public hospital in Jahra, west of Kuwait City, on experimental basis for six months.

Jordanian prosecutors on Tuesday charged 13 men with carrying out "terrorist" acts for their alleged roles in riots in the southern city of Maan over a double murder there.

Military state security court prosecutors accused the 13 suspects from the restive city of carrying out "terrorist acts by using flammable materials (in the riots) as well as rioting and unlawful assembly," a court official told Agence France Presse.

Incoming Palestinian prime minister Rami Hamdallah, who has been tasked with forming a new government, is likely to present his cabinet line-up "in the coming few days," president Mahmoud Abbas said on Tuesday.

"I asked him to form a new government and in the coming few days, he will finish his consultations and declare a new government," Abbas told reporters in the West Bank city of Ramallah, just two days after he tasked the respected academic with piecing together a new cabinet.