The United Kingdom's interior minister Priti Patel says she had banned the Palestinian militant group Hamas in a move that brings the country's stance on Gaza's rulers in line with the United States and the European Union.
"Hamas has significant terrorist capability, including access to extensive and sophisticated weaponry, as well as terrorist training facilities," Patel said in a statement.
"That is why today I have acted to proscribe Hamas in its entirety."
The organisation will be banned under the Terrorism Act and that anyone expressing support for Hamas, flying its flag or arranging meetings for the organisation would be in breach of the law, the interior ministry confirmed.
Patel is expected to present the change to parliament next week.
Hamas - full name the Islamic Resistance Movement - has political and military wings.
Founded in 1987, it opposes the existence of Israel and peace talks, instead advocating "armed resistance" against Israel's occupation of the Palestinian territories.
Until now the UK had banned only its military arm -- the Izz al-Din al-Qassam Brigades.
Hamas political official Sami Abu Zuhri said the UK's move showed "absolute bias toward the Israeli occupation and is a submission to Israeli blackmail and dictations".
"Resisting occupation by all available means, including armed resistance, is a right granted to people under occupation as stated by the international law," Hamas said in a separate statement.
Israeli Prime Minister Naftali Bennett welcomed the decision, saying in a Twitter post: "Hamas is a terrorist organisation, simply put. The 'political arm' enables its military activity."
Hamas and Israel clashed most recently in a deadly 11-day conflict in May.
Interior minister Patel was forced to resign as the UK's international development secretary in 2017 after she failed to disclose meetings with senior Israeli officials during a private holiday to the country, including then-opposition leader Yair Lapid.
Lapid, now Israel's foreign minister, hailed the decision on Hamas as "part of strengthening ties with Britain".
Hamas is on the US list of designated foreign terrorist organisations.
The European Union also deems it a terrorist movement.
Based in Gaza, Hamas won the 2006 Palestinian parliamentary elections, defeating its nationalist rival Fatah.
It seized military control of Gaza the following year.