Outspoken peer Lord Kilclooney has described Israel's actions as a "war crime".
Writing on X/Twitter, he also said the country had been "involved in indiscriminate bombing of civilians".
His comments come just two days after Hamas' unprecedented attack.
Hundreds of people have been killed and thousands wounded on both sides, and aid groups operating in the region say there are needs both in Gaza and Israel.
Humanitarian groups are scrambling to assist civilians caught in the war between Israel and Hamas - efforts that are being complicated by an intensified blockade of Gaza and ongoing fighting.
Israel has increased airstrikes on Gaza and blocked food, fuel and other supplies from entering the territory, a move that raised concerns at the United Nations and among aid groups operating in the area.
Weighing in with his own comments on the conflict, Lord Kilclooney - formerly John Taylor - has criticised the actions of Israel.
Read more:
- Hamas threatens to kill a hostage whenever Gaza civilians hit without warning
- Israel vows retaliation against Hamas will ‘reverberate for generations'
- Lough Neagh: Lord Kilclooney says ownership should be removed from Earl of Shaftsbury
"Israel is now involved in indiscriminate bombing of civilians in Gaza," he wrote.
"This is a war crime which both the UK and EU are supporting."
