Iran said on Monday it was open to indirect talks with the United States, after President Donald Trump had issued an ultimatum for a new nuclear deal.

"The way is open for indirect negotiations," Foreign Minister Abbas Araghchi said, dismissing the prospect of direct talks with Washington "until there is a change in the other side's approach towards the Islamic republic".

Istanbul's embattled Ekrem Imamoglu was officially nominated as a presidential candidate by the opposition CHP party for the 2028 elections, a party spokesman told AFP on Monday.

The Republican People's Party (CHP) -- the main opposition party and the second largest party in parliament -- held a primary election on Sunday, at which the only candidate was Imamoglu, the main political rival of President Recep Tayyip Erdogan. Imamoglu has been arrested, interrogated, jailed and stripped of his mayorship in less than a week following a graft and terror probe that the opposition has slammed as a political "coup."

Turkish authorities detained several journalists from their homes, a media workers' union reported Monday, in what it said was a crackdown amid escalating protests triggered by the imprisonment of the mayor of Istanbul and top rival to President Recep Tayyip Erdogan.

On Sunday, a court formally arrested Mayor Ekrem Imamoglu and ordered him jailed pending a trial on corruption charges. His detention on Wednesday sparked the largest wave of street demonstrations in Turkey in more than a decade and deepened concerns over democracy and the rule of law in the country.

U.S. and Russian negotiators on Monday sat down for talks in Saudi Arabia on a partial ceasefire in Ukraine, hours after a round of negotiations between U.S. and Ukrainian delegations, Russian news reports said.

The state Tass and RIA-Novosti news agencies said the negotiations had begun in the capital Riyadh. The meeting is expected to be followed by another contact between U.S. and Ukrainian teams.

Donald Trump's Middle East envoy Steve Witkoff said the U.S. president was trying to head off armed conflict with Iran by building trust with Tehran.

Sudan 's military said Friday it retook the Republican Palace in Khartoum, the last heavily guarded bastion of rival paramilitary forces in the capital, after nearly two years of fighting.

The seizure of the Republican Palace, surrounded by government ministries, represents a major symbolic victory for Sudan's military against the paramilitary Rapid Support Forces. However, it likely doesn't mean the end of the war as the RSF holds territory in Sudan's western Darfur region and elsewhere.

Ukraine is hoping to secure a partial ceasefire at upcoming talks in Saudi Arabia during which U.S. officials will meet separately with Russian and Ukrainian representatives, a senior Ukrainian official told AFP on Friday.

"We still want to agree on a ceasefire, at least on what we have proposed," the source said, referring to a Russian and Ukrainian halt on strikes on energy sites, civilian infrastructure and attacks in the Black Sea, adding that the Ukrainian delegation on Monday would be led by Defence Minister Rustem Umerov.

Flights to and from London's Heathrow Airport were canceled Friday after a fire at a nearby substation knocked out power to Europe's busiest airport, disrupting travel plans for hundreds of thousands of people around the world.

Here's a look at what's happening and its impact on air travel.

President Donald Trump 's executive order to facilitate the closure of the U.S. Education Department is met with protests and court challenges. Elon Musk focuses his attention on the Pentagon, where Defense Secretary Pete Hegseth said on social media that the billionaire cost-cutter will discuss "innovation, efficiencies & smarter production." Leaders at dozens of universities facing Trump administration investigations scramble to distance themselves from a nonprofit that helped Black and Latino students pursue business degrees. And the arrests of Canadian and European visitors at U.S. borders has some saying no one is safe to come to America as a tourist anymore.

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President Recep Tayyip Erdogan on Friday said Turkey would not be cowed by "street terror" after days of widespread protests over the detention of Istanbul's powerful opposition mayor, Ekrem Imamoglu.

"Turkey will not surrender to street terror," Erdogan said, as the main opposition CHP called for nationwide protests later on Friday.