Mud and soft ground conditions are severely hampering the progress of Russian and Ukrainian troop movements ahead of a possible new counter offensive by Kyiv, according to UK intelligence.
Russian media outlets are likely exaggerating the effects of the mud as part of an "information operation" aimed at raising Russian morale and undermining Ukraine's supporters, the Ministry of Defence said in a release on Twitter.
The update said surface conditions were likely to improve in the coming weeks as the weather becomes warmer and drier, paving the way for future offensive operations.
The threat from mines was likely to be more telling in hampering combatants' off-road manoeuvring, it added.
It comes as western allies met in the Ramstein airbase in Germany on Friday and formulated plans to provide Ukraine with more ammunition and defence resources.
Before the meeting, Washington unveiled an additional $325 million in new military aid for Ukraine, including additional ammunition for High Mobility Artillery Rocket Systems (Himars), advanced missiles and anti-tank mines.
Separately, Denmark and the Netherlands announced sending 14 German-made Leopard 2 heavy tanks to Ukraine by early next year.
Also before the meeting, Nato Secretary General Jens Stoltenberg told reporters that the bloc had agreed to eventually allow Kyiv to join as a member once the war with Russia ended.
President Volodymyr Zelenskyy pressed Mr Stoltenberg on this point at a meeting in Kyiv on Thursday, and said it was time for the military alliance to open its doors to Ukrainian membership.
Ukraine and Russia conflict latest - in pictures
"I have asked Mr Secretary General to help us overcome our partners' reticence to supply some weapons, namely long-range weapons, modern aviation, artillery and armoured vehicles," Mr Zelenskyy said.
It was revealed that Russia accidentally bombed one of its own cities on Thursday after a Sukhoi-34 supersonic warplane accidentally fired a weapon into the city of Belgorod near the Ukraine border.
Video footage from the site showed piles of broken concrete on the street, several damaged cars and a building with broken windows. One shot showed what appeared to be car upside-down on the roof of a shop.
Belgorod region governor Vyacheslav Gladkov announced a state of emergency overnight and said there was a crater measuring 20 metres (65 feet) on one of the city's main streets. Four cars and four apartment buildings were damaged and three people were injured, he added.
"Thank God there are no dead," Mr Gladkov said on Telegram.
Meanwhile, Britain on Friday imposed sanctions on a Russian judge and four others linked to the arrest and alleged poisonings of Kremlin critic Vladimir Kara-Murza, who was sentenced to 25 years in jail this week for treason and other offences.
Mr Kara-Murza, 41, an opposition politician who holds Russian and British passports, has spoken out against President Vladimir Putin for years and had successfully lobbied western governments to impose sanctions on Moscow and individual Russians for purported human rights abuse.
"Russia's treatment and conviction of Vladimir Kara-Murza once again demonstrates its utter contempt for basic human rights," British Foreign Minister James Cleverly said.
"The UK will continue to support Mr Kara-Murza and his family. I call on Russia to release him immediately and unconditionally."
Britain imposed sanctions on Elena Lenskaya, a judge who it said had approved Mr Kara-Murza's arrest, and two investigators involved in the arrest, Denis Kolesnikov and Andrei Zadachin.
The new British sanctions also target two agents at Russia's FSB security service — Alexander Samofal and Konstantin Kudryavtsev — who it said were involved in poisonings.
All those under sanctions will be subject to British travel bans and will have their assets frozen.
