The Palestinian Islamist group Hamas has been declared a terrorist organisation by the European Court of Justice (ECJ).

Judges in the European Union’s most senior court ruled that the group should remain on an EU-wide blacklist and referred the case back to a lower court.

It came at the end of a long-running court battle to challenge the group’s terror designation, following a previous ruling in 2014 when a lower court annulled the 2001 designation and recommended sanctions on Hamas be lifted.

Judges at the General Court accepted arguments at the time that the EU’s decision was the result of second-hand information from the internet and press rather than an independent investigation, but the finding was appealed by the European Council.

Palestinian high school students show off their skills during a graduation ceremony from a military school course organised by the Hamas security forces and the Hamas Ministries of Interior and Education (Getty) (Getty Images)

A spokesperson for the ECJ said judges ruled that groups may be listed if “there is an ongoing risk of that person or entity being involved in the terrorist activities” and that the Council of the European Union was not legally obliged to undertake its own investigation.

“The ECJ therefore sets aside the 2014 judgement of the General Court,” a statement added.

“It refers the case back to the General Court so that the latter may examine the facts and arguments on which it did not rule in its 2014 judgement.”

In the same session, the ECJ ruled that the Liberation Tigers of Tamil Eelam (Tamil Tigers) should no longer be listed as a terrorist group by the EU because of the reduced risk of terror attacks following the group’s military defeat in Sri Lanka.

The European Jewish Congress welcomed the decision on Hamas, saying the ruling sent an “important political message for the fight against international terror”.

Dr Moshe Kantor, the group’s president, said: “Hamas is a part of an international terror network and has murdered countless people.

“One just needs to look at article seven of their charter to know their proudly stated genocidal aspiration to the mass murder of Jews all over the world.”

The US is among the countries globally that classify Hamas as a terrorist group, although in the UK it is not banned in its entirety.

The Home Office’s list of proscribed organisation includes its military wing, the Izz al-Din al-Qassem Brigades, for their “aims to end Israeli occupation in Palestine and establish an Islamic State”.

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Hamas, which controls the Gaza Strip, has been subject to widespread travel bans and asset freezes since 2001, and has fought several wars against Israel as well as launching insurgent attacks.

It has opposed sanctions and argued it has a legitimate right to conduct military operations, but senior leaders regularly praise “martyrs” who launch terror attacks against Israeli civilians.

Hamas’ founding charter, from 1988, called for the takeover of all territories in former Mandatory Palestine, including modern-day Israel, but a new document presented in May claimed it would accept a Palestinian state within 1967 borders.

The proposal would see Israel hand over East Jerusalem, the occupied West Bank and Gaza Strip, with Jerusalem as the Palestinian capital and refugees dating back to the founding of Israel allowed to return to their homes.

Benjamin Netanyahu’s government blames the group and alleged “incitement” from other Palestinian leaders for a spate of stabbing and shooting attacks targeting Israelis.

Following a terror attack that killed two Israeli police officers outside a holy site in Jerusalem, the decision to instal metal detectors sparked days of violent protests that saw several deaths, sparking fresh alarm in the EU and United Nations.