The EU, UK, and Canada on Tuesday announced fresh sanctions targeting the Myanmar junta's access to "military materiel, equipment and funds".
The new curbs, against entities supplying aviation fuel and equipment to Myanmar's military, were aimed at constraining its "ability to conduct airstrikes on civilians", according to Britain.
It said the month of August saw the highest number of airstrikes on record by the Myanmar military, killing dozens of civilians and amounting to "gross human rights violations".
The sanctions -- the latest by Western countries since a February 2021 military coup ousted Aung San Suu Kyi's government -- target six entities involved in providing aviation fuel or restricted goods to the junta.
They bolster several previous rounds of curbs against suppliers of aviation fuel to the military and arms dealers in 2023.
"The human rights violations taking place across Myanmar, including airstrikes on civilian infrastructure, by the Myanmar military is unacceptable and the impact on innocent civilians is intolerable," junior UK foreign minister Catherine West said.
"That is why today the UK is announcing fresh sanctions targeting the suppliers of equipment and aviation fuel to the Myanmar military.
"Alongside the EU and Canada, we are today further constraining the military's access to funds, equipment and resources."
West added the UK remained "steadfast in our support for the Myanmar people and their aspirations for a peaceful and democratic future".
The UK's Foreign Office in London said Britain had provided more than £150 million ($195 million) in humanitarian assistance, healthcare, education and support for civil society and local communities in Myanmar since the 2021 coup.
Over 3.4 million people have been displaced by the fighting, over 18 million are in need of humanitarian assistance, and Myanmar is now seeing "a proliferation in serious and organised crime", it added.
The latest sanctions come as ethnic minority rebels and "People's Defence Forces" battling to overturn the junta's coup are riding the wave of a huge year-long offensive.
It has ejected the junta from around 50,000 square kilometres -- an area roughly the size of Bosnia -- according to analysts and an AFP tally, putting the rebels in sight of the former royal capital, Mandalay.