A group of Twitter users will be indicted in Saudi Arabia on charges of harming public order for threatening the "safety and moderate ideology of society" through extremism, according to a statement on state news agency SPA.

The country's chief prosecutor summoned the Twitter users on Sunday, the statement said, without naming them or specifying how many were accused.

A spokesman for the Ministry of Culture and Information had earlier tweeted that a radical Sunni cleric, Ali al-Rabieei, had been referred to a "publication crimes" committee for unspecified violations.

Ministry officials did not respond to requests for comment on whether Rabieei was among the group.

Saudi Arabia has stepped up efforts to muffle political dissent in recent years, using tough new cybercrime laws to sentence offenders to prison terms for online posts deemed insulting to rulers or threatening to public order.

In a separate statement, Public Prosecutor Sheikh Saud bin Abdullah al-Muajab said he respected freedom of opinion but asserted his office's power to pursue cases against those who promote hatred or sectarianism, or mislead public opinion.

Rabieei's tweets largely consist of broadsides against Shi'ites, a minority group in Sunni-dominated Saudi Arabia. One tweet refers to the core Shi'ite belief that the prophet's son-in-law was his rightful successor as "one of the Jew's tricks."

He issued a statement on Twitter declaring his commitment to publication laws, "if they are not contrary to the Quran, the Sunna, or statements made by senior scholars Bin Baz, Bin Uthaymin or the Council of Senior Scholars."

Religious scholars from the official Wahhabi school of Sunni Islam, like those named by Rabieei, hold influential semi-legal roles in the kingdom. The Quran and the Sunna, or sayings of the prophet, are the country's constitution.

Many members of the state-employed clergy have long taught that Shi'ism is heretical. Last year, Saudi Arabia's grand mufti, the kingdom's top religious authority, said the leaders of Iran, Saudi Arabia's regional Shi'ite rival, were not Muslims.

But as the kingdom's Shi'ites have come under attack by Islamic State jihadists since 2013, authorities have also made efforts to curb open incitement and sectarianism, including arrests for anti-Shi'ite social media posts.