Eliza Manningham-Buller, who led the domestic spy agency two decades ago, said she agreed with comments made by the Russia expert Fiona Hill, who argued in a Guardian interview earlier this year that Moscow was at war with the west.

Lady Manningham-Buller argued that the situation had changed “since the invasion of Ukraine and the various things I read about that the Russians have been doing here – sabotage, intelligence collection, attacking people and so on”.

Speaking on a podcast in which she was interviewed by the lord speaker, John McFall, she then referenced Hill, who advised Donald Trump during his first term as US president and co-authored the UK’s strategic defence review.

“I think she may be right in saying we’re already at war with Russia. It’s a different sort of war, but the hostility, the cyber-attacks, the physical attacks, the intelligence work is extensive,” she said.

Six Bulgarians living in the UK were jailed this year for their role in a spy ring conducting hostile surveillance around Europe, and five men were convicted for their involvement in an arson attack ordered by Moscow on a warehouse containing supplies destined for Ukraine.

Pat McFadden, then the Cabinet Office minister, said last year that Russia had stepped up its cyber-attacks against the UK. Hackers have targeted a string of British businesses. While the source of the attacks can take time to detect, many are suspected to have originated in Russia.

Several of the UK’s NATO allies in eastern Europe have been affected by recent drone incidents, most notably Poland where 19 unarmed Russian drones crossed into its airspace this month.

During the early part of Manningham-Buller’s period as MI5 chief between 2002 and 2007, there were hopes that Russia under Vladimir Putin would not revert to its Soviet ways and instead become a potential partner for the west.

Manningham-Buller met Putin in 2005 when he came to London after a G8 summit in Scotland, a time when Lord McFall suggested the Russian president was trying to put on a “pleasant face” to impress the leading western nations.

“I wouldn’t quite describe him as that,” Manningham-Buller replied.

“I didn’t anticipate that within a year he’d be ordering the murder on London streets of [Alexander] Litvinenko, but I thought he was quite an unpleasant man.”

Litvinenko, a former Russian FSB spy who lived in London, fell ill and died slowly in 2006 after he was poisoned with radioactive polonium. A public inquiry held a decade later concluded that two Russian agents killed him and that they were probably acting on Putin’s orders.

Manningham-Buller criticised the decisions by the US and UK governments to dramatically cut aid spending, arguing it would create a diplomatic opportunity for China to exploit poorer countries.

She added she had been struck by the quality of the HIV treatment work funded by the US in Africa, which she witnessed during her time a director and then chair of the Wellcome Trust, the medical research charity, after leaving MI5.

“You’d go to a pretty primitive hospital with people on pallets on the ground, but the George W Bush-funded Aids wing was a different scale. For Americans to stop all of that, and for our cutting back on aid, means that we leave space for your friendly Chinese diplomat,” she continued.

“If we withdraw from the world, they can move in because they have a strong economic base, so I think soft power … whether it’s the BBC World Service, whether it’s aid, whether it’s demining, all contribute importantly to our influence in the world, as well as being of humanitarian importance.”