Collective European Union action against Israel over the war in Gaza is “long overdue”, Tánaiste Simon Harris has said.

Mr Harris, the Minister for Foreign Affairs, said there are “clear, concrete measures the EU can take” over the war in Gaza.

He was responding to a letter from more than 200 former EU diplomats and senior officials, and former ambassadors from several national countries, expressing “profound disappointment” that the union has taken “no substantive measures” to pressure Israel to end its “brutal” war.

The letter said if the EU could not jointly agree to take action against Israel, a group of “like-minded” countries should move ahead with their own sanctions.

The former diplomats and officials criticised the amount of aid getting into Gaza as “totally‬‭ inadequate”.

The letter, seen by The Irish Times, said violent settlers were continuing to “run amok” in the West Bank, noting the recent murder of a human rights campaigner in the occupied Palestinian territory.

Several former high-ranking Brussels officials were among the 209 who signed the letter, such as Carlo Trojan, who previously served as the European Commission’s top civil servant.

A number of former Irish officials added their names to the open letter, notably former minister for foreign affairs and Labour leader Eamon Gilmore, who went on to serve as an EU envoy. Other Irish signatories include former EU ambassadors Brian McDonald, Michael Doyle and Sean Doyle.

The letter states malnutrition is threatening the the lives of tens of thousands of people in Gaza and that more than 2,600 Palestinians had been killed there since a previous letter was sent by members of the group last month.

“We note with dismay that, in the ensuing four weeks since our (last) letter, no ceasefire has been agreed in Gaza, no Israeli hostages have been released, and, alarmingly, the Israeli government has begun implementing plans to empty Gaza City and its environs of one million Palestinians, by forcing them into concentration areas in the south, in preparation for possible large-scale deportations to third countries with the risk of fomenting a migration crisis,” the letter states.

The letter was sent to European Commission president Ursula von der Leyen, other senior EU leaders, and the 27 national governments.

A commission spokesman said “all options remain on the table” in how the EU might put extra pressure on Israel. Those options would be discussed when foreign ministers from the 27 states meet in Denmark later this week for talks, he said.

Mr Harris described the letter as a “vital, unprecedented intervention” by former officials. “If we don’t take collective action now against the backdrop of famine, when will we?

“Collective EU action could make a powerful difference.”

In a series of social media posts, the Fine Gael leader said: “In the absence of collective action, groups of members states should seek to work together but this would not be as impactful or effective and be a indictment on our ability to act as a collective at a time when the EU itself has found Israel in breach of the Association Agreement.

“EU Foreign Ministers meet in Copenhagen this week and I look forward to discussing this directly with counterparts.”

The Government has been accused by campaigners of an “absolute refusal to hold Israel accountable for a genocide”.

The Ireland-Palestine Solidarity Campaign has organised a series of demonstrations, with a protest scheduled for Tuesday evening around the Central Bank of Ireland’s role in approving Israeli bonds for sale.

The bank is the designated authority in relation to the sale of Israeli bonds in the EU, and has determined the securities meet the standards of the union’s prospectus regulations.

Israeli bonds have been advertised as supporting the country’s economy and, more recently, websites promoting the securities emphasise their role in supporting Israel’s military operations in Gaza.

Protesters and Opposition parties have called for legislation that would give Ireland the power to refuse the sale of Israeli “war bonds” over human rights concerns.

The Central Bank has said regulations require it to approve prospectuses that meet standards of completeness, consistency and comprehensibility. The Israel bond prospectus is up for renewal on September 2nd.