Twitter users in two Gulf Arab states have been sentenced to prison, according to reports, in the latest sign of widening crackdowns in the region on those using social media.

A Kuwait court sentenced Musaab Shamsah to five years in prison on Monday for a Twitter message posted in May that authorities said insulted the Prophet Muhammad.

The post, since taken down, made references to the Prophet's descendants, reported the Associated Press news agency.

In the second case, Waleed al-Shehhi was jailed for two years and fined $137,000 in the United Arab Emirates for a message posted in May about the trial of 94 men accused of links to an armed group.

Authorities said the message violated state security.

In July, 69 of the defendants were convicted of trying to overthrow the state.

There was no immediate comment from authorities in either country on the cases.

Meanwhile in Saudi Arabia, three lawyers are facing trial over social media posts allegedly criticising authorities.