Britain and the rest of the G7 should urgently agree a tough package of sanctions to impose on China if it escalates military tensions with Taiwan, Liz Truss will argue, as she uses her first public overseas speech to pile pressure on Rishi Sunak. Speaking in Tokyo on Friday, the former prime minister will urge her successor to be more hawkish in standing up to Beijing, warning coordinated action is needed to block “the rise of a totalitarian China” given “the free world is in danger”. Truss is expected to raise concerns about the threat to Taiwan’s independence, saying the self-governed island should have its diplomatic status upgraded by being accepted into international organisations. Other calls to action Truss will make as part of a six-point plan being presented to a conference in Tokyo include the creation of “an economic Nato” and regular audits by democratic countries to reduce dependence on China across critical industries. Her speech is a further attempt to rebuild her political reputation, after resigning in October and becoming the UK’s shortest-serving prime minister. However, it will also be viewed as an attempt to put pressure on Sunak to ensure a promised update to the government’s defence and security plan, known as the integrated review, and a stronger stance on China. Truss herself ordered the review be updated only 18 months after the strategy – meant to look ahead to the next decade – was published, with suggestions China would be reclassified as a “threat” instead of a “systemic challenge”. During the summer Conservative leadership contest, the then foreign secretary and her allies sought to present her as more hawkish in standing up to Beijing and less enticed by closer economic ties, given concerns about human rights abuses in Xinjiang, the erosion of democracy in Hong Kong and military tensions with Taiwan. Sunak has backed away from escalating a diplomatic row with China, but stressed in November that the so-called “golden era” of relations was over. Defence and foreign affairs officials in Whitehall believe that China is closely watching the west’s response to Russia’s invasion of Ukraine, and acknowledge that deep economic sanctions were in part designed to deter other potential aggressors. But Russia’s economy is substantially smaller, and any sanctions against China would carry potentially much greater consequences for the global economy. The Guardian revealed earlier this week that government officials were strategising a series of scenarios about the economic fallout if China invaded Taiwan – both due to the disruption to supply chains of items like microchips and the impact of sanctions. China’s government claims Taiwan as a province, and its authoritarian premier, Xi Jinping, is set on what he terms “reunification”. Truss herself will admit that having “rolled out the red carpet” for Xi on his state visit in 2015, when she was a cabinet minister, was a mistake. In her speech to the Inter-Parliamentary Alliance on China symposium, she is will say: “I should know – I attended a banquet in his honour. Looking back, I think this sent the wrong message.” Taiwan is a “beacon of freedom” and “flourishing democracy, with a thriving free press and an independent judiciary”, Truss will stress, adding that the UK should “learn from the past” and “ensure that Taiwan is able to defend itself”. Some Conservatives still want Sunak to take a more lenient approach to China. Philip Hammond, a Tory peer and former chancellor under Theresa May, gave a speech to the China-Britain Business Council on 8 February where he acknowledged “the background noise” to the UK and China’s relationship over the last three years “has been challenging”, but said political differences should “not become an impediment” to boosting trade ties. “Quite honestly, if we only trade with people with whom we have no political differences, we can close half our ports tomorrow,” Hammond added. • This article was amended on 20 and 24 February 2023. An earlier version contained comments said to be from an article written by Philip Hammond for China Daily suggesting the UK and China should “return to business as usual”. After publication Hammond informed us that he had not written any article, rather that the newspaper had published an altered version of his speech to the China-Britain Business Council under his byline, and the phrase “business as usual” had in fact been a reference to a return to in-person meetings after the pandemic.