Zakharova made the comments after a Ukrainian source told Reuters last week that US and Ukrainian officials had been discussing a proposal for an air ceasefire to take to Russian counterparts as part of a new round of peace talks.
The Kremlin said earlier on Monday that it had not seen any specific information regarding new peace proposals ahead of a planned meeting on Tuesday in Washington DC between US President Donald Trump and Ukrainian President Volodymyr Zelenskiy.
New UK Prime Minister Andy Burnham welcomed Zelenskiy as his first international visitor on Monday in a move that underscores the UK's steadfast support for Ukraine, Burnham's office said.
The two leaders met at a naval base, where they were due to hear how UK-led training programs are helping strengthen Ukraine's armed forces and deliver results on the battlefield, according to Downing Street.
"Britain stands with Ukraine, shoulder to shoulder, and our support remains unwavering," Burnham said in a statement.
"Russia should be in no doubt of our resolve, and we will not back down until we achieve long-lasting and just peace for Ukraine."
During the visit, Burnham and Zelenskiy were due to meet more than 200 Ukrainian military personnel and sailors who have spent the past three weeks in the UK taking part in Exercise Sea Breeze, a maritime security and counter-mine exercise designed to prepare participants for future missions in the Black Sea.
Since Russia's full-scale invasion in 2022, the UK's total support for Ukraine has reached 25 billion pounds ($A47.5 billion), including 16 billion pounds in military assistance and 5.6 billion pounds in non-military support, Burnham's office said.
On Monday, Burnham, who was speaking alongside Zelenskiy, said the UK would provide new home-grown jamming technology to protect Ukrainian drones in the war.
Burnham's predecessor Keir Starmer visited Kyiv days before he stood down earlier this month, where he pledged 300 million euro ($A492 million) to help equip Ukraine with a squadron of 16 Swedish-made Gripen fighter jets.
