Two boats carrying dozens of international activists sailed into the Gaza Strip on Saturday in defiance of an Israeli blockade, receiving a warm welcome from thousands of jubilant Palestinians, after a two-day journey marred by communications troubles and rough seas.

On Sunday, Hamas security officials were seen guarding the boats as they lay in port. Since setting sail from Cyprus early on Friday, the mission by the US-based Free Gaza Movement had been experiencing problems.

Israel initially hinted it would prevent the vessels from reaching Gaza, and on Saturday, the group accused Israel of jamming its communications equipment. But late on Saturday, Israel said it would permit the boats to dock in Gaza, after determining the activists did not pose a security threat.

The group delivered a symbolic shipment of hearing aids and balloons. The Israeli Interior Minister, Meir Sheetrit, said Israel had made the right decision to let the activists in.

"Instead of creating a fight which will upgrade the action against Israel, it's better to let them in, then nobody is any more interested in what they have to do and what they have to say," Sheetrit said, speaking in Jerusalem on Sunday.

AP Television footage on Sunday showed activists arriving at Shifa hospital in Gaza Strip. They were given a tour of the hospital and were shown the Israeli weapons which were fired into the Gaza Strip. They also visited patients in the hospital.

Later in the day Gaza's Hamas Prime Minister, Ismail Haniyeh welcomed the activists in his residence by announcing that the group were able to make more frequent visits to the region. "We will issue all the members of the group with Palestinian passports," Haniyeh told the activists.

Israel imposed its blockade in June 2007 after the Islamic movement Hamas violently seized power in Gaza.

Israel considers Hamas, which is committed to the Jewish state's destruction and has killed more than 250 Israelis in suicide bombings, a terrorist group.

Under the blockade, Israel has closed its trade crossings with the territory, while neighbouring Egypt sealed its passenger crossing, confining Gaza's 1.4 million residents.

Israel has allowed little more than basic humanitarian supplies into Gaza, causing widespread shortages of fuel, electricity and basic goods. Only a trickle of people are allowed to leave Gaza for medical care, jobs abroad and the annual Muslim pilgrimage to Saudi Arabia.

The 70-foot Free Gaza and 60-foot Liberty left Cyprus early on Friday for the voyage, which was meant to draw attention to the effects of the blockade.

The 46 activists, from 14 countries, include an 81-year-old Catholic nun and Lauren Booth, the sister-in-law of international Middle East envoy and former British Prime Minister Tony Blair. The activists were the first foreigners to break the blockade.

Organisers said they would stay in Gaza for 24 hours, though it remained unclear how they planned to leave. Israel controls all movement in and out of Gaza.