"This is baseless speculation from Russia and we will not dignify it by commenting further," a spokesperson for Britain's foreign ministry said in emailed comments.
Russia's deputy UN ambassador Dmitry Polyanskiy said on Monday, without providing any evidence, that British intelligence services might have been involved in the attack that killed two, injured a girl, and damaged the bridge.
"I have not heard any condemnation of this act of terrorism from any of the Western sponsors of the Kyiv regime," Polyanskiy told the United Nations Security Council.
"And we have yet to figure out to what extent Western, in particular British intelligence agencies, were involved in the preparation and implementation of this terrorist attack. Too many things point to that."
Early on Monday, a blast knocked out the bridge linking Russia to the Crimean Peninsula, which Moscow annexed from Ukraine in 2014, in what Moscow called a strike by Ukrainian sea drones.
The accusation comes as Britain introduced new sanctions, including against Russian Education Minister Sergey Kravtsov, related to what it described as Moscow's forced deportation of Ukrainian children.
Britain imposed 13 new sanctions designations in response to "Russia's attempts to destroy Ukrainian national identity", some of which it said were linked to the forcible relocation of children. They will be subject to asset freezes and travel bans.
"In his chilling programme of forced child deportation, and the hate-filled propaganda spewed by his lackeys, we see (Russian President Vladimir) Putin's true intention - to wipe Ukraine from the map," British Foreign Secretary James Cleverly said in a statement on Monday.
"Today's sanctions hold those who prop up Putin's regime to account, including those who would see Ukraine destroyed, its national identity dissolved, and its future erased."
Russia's embassy in Britain called the new sanctions "categorically unacceptable and legally null", and said in a statement the people sanctioned included those who had taken part in the rescue of children.
An EU sanctions package last month included those the bloc said were responsible for "the forced transfers and deportation of Ukrainian children and persons responsible for the looting of Ukraine's cultural heritage".
In June 2022, Britain also sanctioned Russian Children's Rights Commissioner Maria Lvova-Belova for the forced transfer and adoption of Ukrainian children.
Britain says many of the children have been sent to re-education camps, where they are "exposed to Russia-centric academic, cultural, patriotic, and military education".
Earlier this month Russia said it had brought some 700,000 children from the conflict zones in Ukraine into Russian territory for their own protection.
Ukraine has managed to return some of them but says many are considered illegally deported, without permission from their parents or Ukrainian authorities.
Russian culture minister Olga Lyubimova was also sanctioned on Monday "for using her position to support the Russian state's damaging anti-Ukrainian policies", Britain said.
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