The 22-year-old woman was held under the Terrorism Act on suspicion of "supporting a proscribed organisation", Counter-Terrorism Policing South East said.

It comes after an investigation into a speech made by a woman at a protest in Brighton on Sunday.

The University of Sussex confirmed the arrested woman - who has now been bailed until next month - was one of its students.

"The university takes very seriously our obligations to support students and staff and to provide a safe and secure environment in which to work, live and study, and will continue to take action to this end," it added.

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Hamas IDQ, the military wing of Hamas, has been categorised as a terrorist group by the US, UK and EU.

In Britain, it was proscribed by the Home Office in March 2001 and the ban was extended to cover the whole of Hamas two years ago.

The escalating violence in the Middle East has seen protesters taking to the streets of Britain and around the world, with some waving Palestinian flags and chanting anti-Israel slogans.

On Saturday, more than 1,000 officers will be on duty to police a pro-Palestinian protest in central London on Saturday.

The Metropolitan Police said it was expecting thousands of people to travel to the demonstration, which starts at 12pm and is due to finish in Whitehall at 3pm.

Deputy Assistant Commissioner Laurence Taylor said: "People do not have the right to incite violence or hatred. The law is clear that support for proscribed organisations is illegal.

"Anyone with a flag in support of Hamas or any other proscribed terrorist organisation will be arrested. We will not tolerate the celebration of terrorism or death, or tolerate anyone inciting violence.

"We have seen behaviours this week that are unacceptable. They are hateful and there is no place for that in London."

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Home Secretary Suella Braverman has suggested waving the Palestinian flag "may not be legitimate" and immigration minister Robert Jenrick said foreign nationals could be deported if they commit antisemitic acts or praise Hamas.

But the Met Police said it had written to the Attorney General and Crown Prosecution Service to clarify what constituted a criminal offence in these situations.

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A force spokesman added: "An expression of support for the Palestinian people more broadly, including flying the Palestinian flag, does not, alone, constitute a criminal offence.

"However, there are some situations where the presence of a flag or banner or the use of specific words or phrases could be seen as intimidation. In some circumstances, it could also be seen as intending to cause harassment, alarm or distress."

It comes as a coalition of activists and charities raised concerns about Government ministers' rhetoric since the crisis began.

In a letter to Prime Minister Rishi Sunak, groups such as Black Lives Matter, the Muslim Association of Britain and the Sri Lankan Diaspora UK raised concerns that the language used by the home secretary and Foreign Secretary James Cleverly could leave Britain "complicit in massacres...and ethnic cleansing".