It's after the resignation of Edouard Philippe who has been in the post for three years.
Mr Castex, 55, is relatively unknown in France, although he is a senior civil servant.
The new Prime Minister has been a key player in the government's response to the Covid-19 pandemic.
Philippines confirms visit by alleged Bondi gunmen amid terrorism concerns
The Philippines Bureau of Immigration said on Tuesday that the two alleged gunmen behind the mass shooting at Sydney's Bondi Beach travelled to the Philippines, just weeks before the assault that killed 15 people.
Israeli forces kill Palestinian teen in West Bank, health ministry says
The Israeli military have shot dead a 16-year-old Palestinian during a raid on the town of Tuqu' on Monday, the Palestinian health ministry said, the latest deadly incident in a recent surge of violence in the Israeli-occupied West Bank.
Trump sues BBC for defamation, seeks up to $10 billion in damages
US President Donald Trump has sued the BBC on Monday for defamation over edited clips of a speech that made it appear he directed supporters to storm the US Capitol, opening an international front in his fight against media coverage he deems untrue or unfair.
FBI foils 'terror plot' targeting Los Angeles
Four people are facing criminal charges in connection with what Attorney General Pam Bondi described on Monday as a foiled bomb plot that contemplated multiple targets, including US immigration agents and their vehicles.
The UAE is set to significantly widen its ban on single-use plastics, with the second phase coming into effect on January 1, 2026.
UAE President His Highness Sheikh Mohamed bin Zayed Al Nahyan has led messages congratulating Bahraini King Hamad bin Isa Al Khalifa on the country's national day, which falls on December 16.
Three cancer drugs will be produced in the UAE in Mubadala Bio's new facility, marking a major step in "enhancing drug security and availability of cost-effective treatment options for patients" in the country.
