Eight people, including an Iranian-born British woman, have been jailed in Iran on charges including blasphemy and insulting the country's supreme leader on Facebook.

The opposition website Kaleme reported that two of the eight, identified as Roya Saberinejad Nobakht, 47, from Stockport, and Amir Golestani, each received 20 years in prison and the remaining six – Masoud Ghasemkhani, Fariborz Kardarfar, Seyed Masoud Seyed Talebi, Amin Akramipour, Mehdi Reyshahri and Naghmeh Shahisavandi Shirazi – between seven and 19 years.

They were variously found guilty of blasphemy, propaganda against the ruling system, spreading lies and insulting Ayatollah Ali Khamenei.

Nobakht's husband, Daryoush Taghipoor, told the Manchester Evening News in April that his wife had been detained at the airport in Shiraz last October in connection with comments she had made on Facebook.

It was not clear whether the eight had access to lawyers for their trial. Kaleme said the intelligence services of the elite Revolutionary Guards had arrested them last year and put them under pressure to admit to their crimes on camera, a common tactic in the Islamic republic.

"We are aware that a British national has received a custodial sentence in Iran," a Foreign Office spokesperson said. "We are seeking to establish the full facts and are following up the case with the Iranian authorities."

There is a growing row between President Hassan Rouhani's administration, which favours internet freedom, and hardliners wary of relaxing online censorship. Last week, Iran's national TV paraded six young Iranians arrested for performing a version of Pharrell William's hit song Happy and posting a video of it on the internet. The arrests caused global outrage and prompted Rouhani to react in their support. The performers were soon released, but the video's director, Sassan Soleimani, remains in jail.

The arrests highlighted the challenges Rouhani faces in delivering his promise of allowing people greater access to social networks such as Facebook and Twitter, which remain blocked in Iran.

On Tuesday, local news agencies reported that a judge in a southern Iranian province had summoned Facebook's founder, Mark Zuckerberg, to the court in connection with a lawsuit involving privacy violation on Instagram and WhatsApp. There is no extradition treaty between Iran and the US.

In recent weeks Rouhani has stepped up his rhetoric in support of internet freedom. "The era of the one-sided pulpit is over," he said recently at a conference in Tehran, endorsing social networks and asking his communications minister to improve bandwidth in the country.

He intervened when the authorities blocked access to the mobile messaging service WhatsApp, ordering the ban to be lifted. Iran's judiciary, which is a political institution independent of the government, has since moved to challenge Rouhani's intervention and orderered WhatsApp to be banned.

Until two years ago, Iran's ministry of information and communications technology was in charge of policing the country's online community, but in 2012 Khamenei ordered officials to set up the supreme council of virtual space, a body that is closer to the supreme leader than to the government. This means Rouhani is not the sole decision-maker in the future of Iranian web.

With help from Iran's cyberpolice, the judiciary and the Revolutionary Guards have identified and arrested Iranians because of web-related issues, including several employees of the Iranian gadget news website Narenji, who have been in jail since December.

It emerged this week that Iran's cyberpolice had blocked access to a blog-hosting service that refused to comply with a request to hand over private information belonging to one of its users. It was not clear whether the authorities obtained a court order to apply the block.