Thousands of demonstrators have marched in support of Palestine to the New York office of the American Israel Public Affairs Committee (AIPAC), a powerful pro-Israel advocacy group, to protest its role in obstructing a ceasefire resolution in the Gaza war.

Protesters held banners on Thursday declaring “AIPAC funds genocide”, while participants chanted “Free Palestine”, “Let Gaza live”, “Stop the genocide” and “Ceasefire now”.

Jewish Voice for Peace, an antiwar group, said that 18 Jewish activists were arrested for “shutting down” the New York offices of Democratic senators Chuck Schumer and Kirsten Gillibrand.

The United States this week vetoed another United Nations Security Council draft resolution on Israel’s war on Gaza, blocking a demand for an immediate ceasefire between Israel and Hamas.

Arab nations, led by Algeria, put the draft resolution to a vote on Tuesday with the expectation that it would not pass after the US – Israel’s key ally – had warned it would not back the text and proposed a rival draft instead.

The US was the only country to vote against the draft text while the United Kingdom abstained. The UN Security Council’s 13 other member countries voted in favour of the text demanding a halt to the war that has killed more than 29,000 people in Gaza, according to Palestinian authorities, and displaced more than 80 percent of the population.

Linda Thomas-Greenfield, the US ambassador to the UN, rejected claims that the veto was a US effort to cover for an imminent Israeli ground invasion into the southernmost Gazan city of Rafah, where some 1.4 million displaced people are sheltering.