Ukrainian President Volodymyr Zelensky urged the United States on Tuesday to levy its most hard-hitting package of sanctions on Moscow if Russian President Vladimir Putin rejects a call to meet in Turkey this week.

Iran is open to accepting temporary limits on its uranium enrichment, its deputy foreign minister said Tuesday, while adding that talks with the United States have yet to address such specifics.

Russia has been "completely ignoring" a 30-day unconditional ceasefire proposed by Kyiv and its allies and is attacking "all along" the front line, Ukrainian Foreign Minister Andriy Sybiga said Monday.

Turkey's Foreign Minister Hakan Fidan on Monday urged Russia and Ukraine to come together "as soon as possible" to start a ceasefire agreement ahead of planned talks in Istanbul this week.

"We invite the parties to come together as soon as possible and start the ceasefire," he told a joint press conference in Ankara with his Syrian and Jordanian counterparts

The Kremlin on Monday said "ultimatums" to agree to a ceasefire in Ukraine were "unacceptable" after EU leaders said Moscow had until midnight Monday to agree to a joint proposal with Kyiv for a 30-day halt to the fighting.

The Kremlin said Monday it was focused on "serious" ways to achieve long-term peace with Ukraine, but did not comment on Ukrainian leader Volodymyr Zelensky's invitation for a personal meeting with Vladimir Putin.

The Kurdistan Workers' Party (PKK) on Monday announced its dissolution, saying it was ending its armed struggle against the Turkish state and drawing a line under its deadly four-decade insurgency.

Iran and the United States wrapped up nuclear talks in Oman on Sunday with no apparent breakthrough in a public standoff over enrichment, but with both sides confirming plans for future negotiations.

Ukrainian President Volodymyr Zelensky on Sunday urged Russia to accept a 30-day truce proposed by Kyiv's allies, adding he expected Russian President Vladimir Putin to attend peace talks in Turkey.

Iran's Foreign Minister Abbas Araghchi said Sunday he hoped the fourth round of nuclear talks with the United States would reach a "decisive point".