The Trump administration has stepped up its support for protesters in Iran by calling on the government to stop blocking social media sites and encouraging Iranians to use special software to circumvent controls.

Following several days of tweets by President Donald Trump urging on the protesters and declaring that it’s “time for change,” the State Department took it further, arguing that the United States has an “obligation not to stand by”.

Under-secretary of state Steve Goldstein, in charge of public diplomacy, said the US wants Iran’s government to “open these sites” including the photo-sharing platform Instagram and the messaging app Telegram.

“They are legitimate avenues for communication,” Mr Goldstein said. “People in Iran should be able to access those sites.”

Iranians seeking to evade the blocks can use virtual private networks, Mr Goldstein said.

Known as VPNs, the services create encrypted data “tunnels” between computers and are used in many countries to access overseas websites blocked by the local government.

Despite the blocks, the US is working to maintain communication with Iranians in the Farsi language, including through official accounts on Facebook, Twitter and other platforms.

The State Department was to distribute videos of top US officials encouraging the protesters through those and other sites.

The US outreach came as the Trump administration, in a departure from President Barack Obama’s approach, was mounting a full-throated show of support for Iranians protesting against the government over concerns about corruption, mismanagement and economic woes.

Iran’s government has blamed the US, Saudi Arabia and the United Kingdom for fomenting the protests, calling them the work of foreign “enemies of Iran”.

Mr Goldstein said the US was not only supporting the protesters but encouraging other countries to do the same.

The State Department was also dispatching Arabic speakers to appear on Arabic-language television networks to discuss the protests in Iran.

“We want to encourage the protesters to continue to fight for what’s right and to open up Iran,” Mr Goldstein said.

The demonstrations over six days have been the largest seen in Iran since its disputed 2009 presidential election, expanding to several cities. At least 21 people have died and hundreds have been arrested.