Ukraine reports the deadliest 24 hours of the war for Russian troops as Moscow hurls tens of thousands of freshly mobilised soldiers and mercenaries into relentless assaults in the east.

BATTLEFIELD LATEST

* Ukraine's governor of the mainly Russian-occupied Luhansk province says Russia is pouring in reinforcements for an offensive that could begin as soon as next week.

* Fierce battles in Ukraine's Donetsk region "are very difficult," Ukraine's President Zelenskiy says, as Kyiv braces for a possible Russian offensive this month before the first anniversary of its invasion of Ukraine.

* Russia says it has taken control of Mykolaivka, a village in Ukraine's eastern Donetsk region, state media reported.

* Russia seems to have tried to restart major offensive operations since early January but is unlikely to be able to gather sufficient forces to significantly affect the war in the next few weeks, a British intelligence report says.

* Russia says it is examining the alleged use of chemical weapons by Ukrainian forces near the eastern towns of Soledar and Bakhmut. Ukrainian forces deny they ever use such weapons.

DIPLOMACY

* Russia says Western arms shipments to Ukraine are dragging military alliance NATO into the conflict with a potentially "unpredictable" level of escalation.

* Switzerland is close to breaking with centuries of tradition as a neutral state, as a pro-Ukraine shift in the public and political mood puts pressure on the government to end a ban on exports of Swiss weapons to war zones.

* The Paris mayor says there should be no Russian delegation at the Paris 2024 Olympics as long as the war is ongoing.

* Zelenskiy has been invited to take part in a summit of European Union leaders.

* The head of the U.N. nuclear agency, the IAEA, will visit Moscow this week, but the Kremlin said he will not meet President Vladimir Putin.

* Ukraine's main Catholic church said it would move to a new calendar that would see Christmas celebrated on Dec. 25 rather than Jan. 7, amid an effort by Ukrainian institutions to break cultural links to Russia.

FATE OF DEFENCE MINISTER

* Ukraine sent mixed messages about the fate of Defence Minister Oleksii Reznikov, leaving a key post in doubt.

* Zelenskiy has fired a series of high-level officials this year in a purge aimed at clamping down on corruption. Reznikov had been under pressure over a corruption scandal.

* Kyrylo Budanov, tipped to be Ukraine's next defence minister, is a young officer who enjoyed a meteoric rise to become military intelligence chief. (Compiled by Reuters editors)