The UK has announced sanctions on six allies of Syrian president Bashar al-Assad, the latest in a flurry of measures and court actions taken against the Damascus regime in Paris, London and Moscow.

Monday marks the tenth anniversary of the uprising against the Assad regime. Protesters took to the streets in March 2011 but were brutally suppressed by the regime, sparking a civil war that drew in world powers and has seen half a million people killed and about half of the country’s population displaced or become refugees.

While Assad has regained control of much of the country, a UN-led peace process is deadlocked while foreign powers directly involved — opposition-backing Turkey, and regime-supporters Iran and Russia — conduct their own talks. Western countries have largely been sidelined.

In its first sanctions against Syria since leaving the EU, London said it would freeze UK assets and ban travel to Britain for six Syrians, including new foreign minister Faisal Miqdad, Assad media adviser Luna al-Shibl, and “influential businessperson and financier” to Assad, Yasser Ibrahim.

“The Assad regime has subjected the Syrian people to a decade of brutality for the temerity of demanding peaceful reform,” Dominic Raab, UK foreign secretary, said as he announced the sanctions.

In recent months, efforts to pursue accountability against the government in Damascus have widened, with a German court the first to jail an alleged Syrian war criminal last month. He was tried on the basis of German laws that recognise universal jurisdiction for war crimes, crimes against humanity and genocide.

Pursuing justice for war crimes in Syria at the international level has long been problematic, but in 2016 UN member states set up an international mechanism to gather and analyse evidence of war crimes for prosecution. This is expected to be critical to trials in Germany and elsewhere.

The British law firm Guernica 37 International Justice Chambers said this weekend it had filed a complaint with London’s Metropolitan Police against Syria’s first lady, Asma al-Assad. The lawyers want the Met to investigate the British-Syrian former banker, alleging “incitement and encouragement to commit acts of terrorism” in Syria. The Met confirmed its War Crimes Unit was assessing “a referral . . . relating to the ongoing Syrian conflict” in late July.

Last week, the brother of a Syrian man who was killed and mutilated filed a complaint to the Russian Federation’s Investigative Committee, accusing a member of Russian private military contractor Wagner of participating in the killing. It represents “a first-ever attempt by the family of a Syrian victim to hold Russian suspects accountable for serious crimes committed in Syria”, said three nongovernment organisations mounting the case.

“The Russian government must assume its legal and moral responsibilities,” said Mazen Darwish, founder of the Syrian Center for Media and Freedom of Expression. “It is simply not permissible to regard the blood of Syrians as cheap.”

As well as the Russian case, Darwish’s group filed a criminal complaint to investigative judges in France implicating the Syrian regime in chemical weapons attacks near Damascus in August 2013. The Syrian government denies committing the crimes and a UN-backed report did not attribute blame.

Dima Moussa, a Syrian opposition politician now based in Turkey, praised the cases as “important and resonant among Syrians”, but added that they also allowed “the international community to show that it is doing something — anything — while evading their required responsibility in reaching a real and sustainable solution”.