The UK has also confirmed the deaths of medic Craig Mackintosh and ex-paratrooper Simon Lingard, who was killed near Bakhmut in eastern Ukraine this month.
The G20 gathering will inevitably be overshadowed by Moscow's offensive in Ukraine, which has shocked global energy markets and aggravated food shortages.
The British government said on Thursday it had frozen assets worth more than 18 billion pounds ($20.5 billion) held by Russian oligarchs, other individuals and businesses sanctioned over Moscow's invasion of Ukraine.
Britain is stepping up its support for Ukrainian soldiers through the winter as a key battle in Kherson looms and as mobilised Russian troops struggle, British Defence Secretary Ben Wallace told Reuters on Wednesday.
President Volodymyr Zelenskiy on Tuesday night said his forces would not yield "a single centimetre" in battles for control of eastern Donetsk region while Russian-installed officials described Ukrainian forces moving into one southern town with tanks.
Stoltenberg will meet Sunak after visiting a military facility where Ukrainian troops are being trained by British military.
Russia said on Wednesday it would resume its participation in a deal freeing up grain exports from Ukraine, reversing a move that world leaders warned would increase hunger globally.
The cost of Russia's military mobilisation and the impact of Western sanctions are set to blow a hole in the government's budget forecasts and drain Moscow's reserves to their lowest level in years, according to analysts' latest calculations.
Olena Zelenska told thousands of investors, entrepreneurs and tech workers gathered for the annual Web Summit in Portugal that Russia "puts technology at the service of terror".
A senior Ukrainian official predicted "the heaviest of battles" to come for the partially Russian occupied strategic southern province of Kherson and said Moscow's military is digging in to face advancing Ukrainian forces.
More than 100 Ukrainian women are testifying to their government regarding their traumatic experience with the Russian soldiers.
The EU on Monday stepped up its military support for Kyiv by launching a mission to train 15,000 Ukrainian soldiers and providing 500 million euros more for weapons.
The European Union prepared to slap sanctions on Iran on Monday over a human rights crackdown and several ministers warned of separate, new sanctions if Tehran's involvement in Russia's war on Ukraine was proven.
Intense fighting between Russian and Ukrainian forces was taking place around two towns in the Donetsk region of eastern Ukraine, Bakhmut and Soledar, Ukrainian President Volodymyr Zelenskiy said on Sunday.
The first group of such volunteer recruits arrived in July and more than 5,700 have already taken the course.
Leaders from the Group of Seven (G7) rich nations have assured Ukrainian officials that they will continue to provide financial support for Ukraine as it battles invading Russian forces, Germany's finance minister said on Thursday.
IMF chief Kristalina Georgieva said Ukraine's financing needs in 2023 will range between $3 billion and $4 billion a month.
Tens of thousands of Russians have fled since Putin sent troops to Ukraine in February and then announced a nationwide military call-up in September.
The United Nations General Assembly voted on Monday to reject Russia's call for the 193-member body to hold a secret ballot later this week on whether to condemn Moscow's move to annex four partially occupied regions in Ukraine.
The UN secretary-general, as the leading defender of the world body's values, bluntly denounced the annexations.
Victoriia Maslova abandoned her herbal cosmetics factory in the Ukrainian town of Bucha on the first day of Russia's invasion of the country, fleeing to Poland with her mother and three younger brothers when rockets began hitting a nearby airport.
France has repeatedly been in critics' sights over its lower level of military support to Ukraine compared with allies.
