A 16-year-old Syrian refugee has been arrested in Germany on suspicion of having ties to the Islamic State jihadist group, officials said Wednesday, describing him as a "serious threat."

Growing xenophobia and rightwing extremism could threaten peace in eastern Germany, the government warned Wednesday, voicing fears over the impact of a series of attacks against refugees in the region.

Two men allegedly linked to French extremist Rachid Kassim have been charged with "associating with terrorists", Paris prosecutors said Wednesday.

Former French president Jacques Chirac is still in hospital in Paris, his family said Wednesday following rumors that the 83-year-old had died.

"President Chirac is being treated for a lung infection and I want to pay homage to the exceptional quality of the medical teams," Chirac's son-in-law Frederick Salat-Baroux told Agence France Presse.

Seven candidates including ex-president Nicolas Sarkozy were confirmed Wednesday to contest the rightwing primary for France's presidential election next year, officials said.

Sarkozy's main rival will be popular former premier Alain Juppe, with the winner of November's two-round contest expected to be in the driving seat to become president next May.

A mentally disturbed Turkish man wielding a knife tried to storm the Israeli embassy in Ankara on Wednesday but was shot by police before reaching the building, Turkish and Israeli officials said.

The man, armed with a 30-centimeter (12-inch) knife, ran towards the embassy shouting slogans and was shot in the leg, the governor's office in the Turkish capital said in a statement.

The United States on Tuesday charged an Afghan-born American restaurant worker, who was critically wounded in a police shootout, with detonating and planting bombs in New York and New Jersey.

U.S. prosecutors said Ahmad Khan Rahami, 28, carried out twin bombings on Saturday in Manhattan's Chelsea neighborhood and along the route of a U.S. Marine Corps run in the New Jersey town of Seaside Park.

Nigeria's military on Wednesday said regional troops had recaptured a town on the shores of Lake Chad from Boko Haram, but the Islamists claimed to have inflicted heavy casualties.

Army spokesman Sani Usman said its troops and counterparts from the Multi-National Joint Task Force (MNJTF) had "captured Malam Fatori... after a fierce battle" backed by air support. 

Brazil's former president Luiz Inacio Lula da Silva on Tuesday slammed as a "farce" his pending prosecution for allegedly masterminding the large-scale plundering of the state oil giant Petrobras.

"I am sad because I just learned (Judge Sergio) Moro accepted the charge lodged, even though it is all a farce, a huge lie," the ex-president said from Brazil by videoconference to New York, where his lawyers held a solidarity event for him.

Philippine President Rodrigo Duterte has launched a profanity-filled tirade against the European Union, in his latest riposte to international criticism of the rising death toll in his brutal crackdown on crime.