A man who made social media posts encouraging violent protests in the city has been put behind bars.

Joseph Clark, 45, called for riots on the streets of Brighton during the planned anti-immigration protests this week.

But instead, he received a knock on the door from specialist police officers trawling the internet for information on the demonstration - and is now spending the next 14 weeks in prison.

Thousands turned out in Brighton on Wednesday eveningThousands turned out in Brighton on Wednesday evening (Image: Sussex News and Pictures)

Sussex Police's assistant chief constable Paul Court said people who send threatening messages on the internet "cannot hide behind their keyboards" and will face the full force of the law.

Officers were first made aware of his post - the contents of which have not been revealed - on Tuesday around 24 hours before protesters were set to descend on an immigration lawyer's office in Queen's Road.

Read more: Police car destroyed after bursting into flames

They arrested two men, Clark and another man aged 42, who was later released.

Clark was charged with sending an offensive message on a public communication network.

The protest largely went by peacefully on WednesdayThe protest largely went by peacefully on Wednesday (Image: The Argus)

He was found guilty at Brighton Magistrates’ Court today and sentenced to 14 weeks in prison, ordered to pay £85 in costs and a £154 victim surcharge.

Read more: 'Do not do it': Police warning as more protests expected tonight in Sussex

Assistant Chief Constable Paul Court added: “This custodial sentence should send a clear message to anyone involved in disorder – either online or on the streets – that they will swiftly face the full force of the law.

“The recent unrest seen across the country has been fuelled by threatening, abusive online messages. Those messages have real world consequences, and those who send them cannot hide behind their keyboards.

“Our preparations are ongoing into reports of planned events across Sussex and we will continue to engage with our communities and provide a visible, reassuring presence.

“Please report any concerns to Sussex Police online or via 101, quoting Operation Skylark.”