Human Rights Watch on Wednesday hit back at Iran's ‘unjustifiable’ decision to ban the Telegram messaging app, warning Tehran against stifling access to information.

‘The Iranian judiciary's blocking of the messaging application Telegram is an unjustifiable restriction on freedom of expression and access to information,’ the US-based rights organisation said in a statement.

Human Rights Watch accused Tehran of ‘stifling access to information to try to make its problems go away’ and said such censorship ‘should never be used to protect leaders from scrutiny’.

A Tehran judge blocked Telegram on Monday, following accusations that the hugely popular app has allowed armed opposition groups to fuel unrest.

The decision was described as ‘just another stain on Iranian authorities' already dismal record on freedom of expression’ by Human Rights Watch.

Telegram is the Iran's most popular social network with some 40 million users, around half the population.

The move to ban the app has highlighted differences of opinion between the government of reformist President Hassan Rouhani and ultra-conservatives who control the judiciary and security services.

Reflecting the government's support of more open access to the internet, telecoms minister Mohammad Javad Azari Jahromi on Tuesday highlighted problems in Russia since authorities there banned Telegram.

‘These problems could happen in Iran as well,’ he said, quoted by the ISNA news agency, after thousands rallied in Moscow on Monday in support of internet freedom.

Despite Telegram being blocked, the app was still easily accessible in Tehran on Wednesday.