Ministers are under pressure to stop using TikTok because of security fears - after the European Commission banned it from work devices.
The EU's executive body has ordered thousands of workers not to use the popular social network - sparking claims the UK government is "dragging its feet" by failing to do the same.
The Houses of Parliament has already stopped using its TikTok account, and US President Joe Biden has brought in a similar ban - but No10 said it has no plans to stop ministers from posting.
Former Tory Party leader Iain Duncan Smith, who no co-chairs the inter-Parliamentary Alliance on China, fumed that the government response was "pretty weak".
And Alicia Kearns, who chairs the Commons foreign affairs committee, called for an outright ban for officials and ministers.
Mr Duncan Smith said: “Even when their Western security operatives show that TikTok poses a security risk to us in the UK, we seem to drag our feet, trying not to take action that might upset China.
“Our response and remedial action have been pretty weak, and now we’re lagging behind with TikTok.
“The prime minister has an opportunity to take control of China policy and it’s a critical time to do so. I hope the government owns up to the danger China poses and takes action immediately on TikTok.”
And Conservative MP Ms Kearns told Politico: “We run the risk of being marooned as a tech security laggard amongst free and open nations.
"The government needs to review its policies and move to ban government officials and parliamentary staff from installing the app on any mobile phones utilized for work, if not any device.”
Luke de Pulford, from the Inter-Parliamentary Alliance on China, told the Daily Mail: 'When it comes to data security, the UK Government is asleep at the wheel.
'MPs have been raising the alarm about TikTok for years, and have been ignored.
'Now the US and EU have both moved and the UK is dragging its feet. The Government shouldn't wait until pushed by the Information Commissioner and should act to protect the data security of government officials immediately.'
But Energy Secretary Grant Shapps, who is one of the most prominent users of the app within government, said he would not be "chased off" TikTok.
The Prime Minister's official spokesman said: "It's a matter for individual departments and ministers to decide what platforms to use."
Announcing its ban, the European Commission said: “This measure aims to protect the commission against cybersecurity threats and actions which may be exploited for cyber-attacks against the corporate environment of the commission.
"The security developments of other social media platforms will also be kept under constant review.”
ByteDance, the privately owned parent company of TikTok, has hit back at claims the app isn't safe.
It said in a statement: “We are disappointed with this decision, which we believe to be misguided and based on fundamental misconceptions.
“We have contacted the commission to set the record straight and explain how we protect the data of the 125 million people across the EU who come to TikTok every month.”
