Two boats carrying more than 40 international human rights advocates landed in Gaza on Saturday, challenging an Israeli blockade of the Hamas-run territory.

About 2,000 residents came out to greet them at the small seaport near Gaza City. Many were singing, while others swam or set out in fishing vessels to meet the boats.

Israel had told the activists to keep their boats away but ultimately decided to allow them to land, apparently to prevent a potentially more damaging public relations drama.

Arye Mekel, an Israeli Foreign Ministry spokesman, said the decision was made “to avoid the provocation they had planned at high sea,” and because the Israeli authorities knew exactly who was on board and what cargo they were carrying.

The human rights advocates, ranging in age from 22 to 81 and coming from about a dozen countries, set sail from Cyprus on Friday morning to make a symbolic stand against what they called Israel’s “illegal” and “immoral” siege of Gaza. They were carrying 200 hearing aids for children in Gaza and thousands of balloons.

Prepared for the possibility that they would be stopped by the Israeli Navy, they said earlier that if they were arrested and taken to Israel, they would “protest and prosecute” their “kidnapping in the appropriate forums.”

Among the passengers was Lauren Booth, a sister-in-law of Tony Blair, the former British prime minister and now a peace envoy for the Middle East; Anne Montgomery, an American nun; and an Israeli Jew, Jeff Halper, a rights activist from Jerusalem.

The Islamic militant group Hamas won Palestinian legislative elections in 2006 and took full control of Gaza last year after a factional war. Since then, Israel has strictly limited the goods allowed into the area, allowing in only basic supplies. Israel, the United States and the European Union classify Hamas as a terrorist organization.

At the seaport, Naama Abu Hamda, 59, said she had come to thank the activists. “We are encouraged by their courage,” she said, “unlike the Arab governments,” who she said had cooperated with the Israeli embargo.

Khalil Nofal, a Hamas leader who also came to the port, said, “This is a strong message to the cowardly Arab leaders.”

Ms. Booth said she was pleased that the Israelis did not block the boats, and hoped that signaled an end of the siege.