Two ships carrying pro-Palestinian activists prepared to be intercepted by the Israeli navy as they neared Gaza on Friday in a fresh attempt to break the blockade on the coastal strip.
The Irish Saoirse (Gaelic for Freedom) and the Canadian Tahrir (Arabic for Liberation) left a port in southern Turkey on Wednesday and were expected to reach Gaza by Friday morning, organisers said.
"The two boats are close to Israeli-controlled waters and those on board have been instructed not to put up any resistance to the Israeli navy when it tries to intercept them," said Denis Kosseim, a spokesman for the Canadian Boat to Gaza campaign.
"Everyone has signed a document in which they pledged not to put up any resistance should they be boarded by Israel," he said.
The two boats are between them carrying 27 passengers and some $30,000 worth of medical aid, as well as journalists and crew members, organisers said.
Palestinian fisherman and supporters had been expecting to welcome the ships into Gaza port at around 9:30 am (0730 GMT).
But by Friday morning, the vessels were still some way off, with a tweet from one of the journalists on board the Irish ship indicating the vessels were 75 nautical miles from the shore.
"The Tahrir and Saoirse are now 75 nautical miles from Gaza. Speed is on average 10 nautical mph. Still no Israeli contact," tweeted Hassan Ghani, correspondent for Iran's Press TV, just before 10:30 am (0830 GMT).
The last boat which tried to reach Gaza was a French-flagged yacht, the Dignity, which was intercepted in July by the Israeli navy some 40 nautical miles off the coast.
An Israeli military spokeswoman said on Friday: "The two boats are approaching and their progress is being monitored by the navy which will establish contact in due course.
"Israel has completed the necessary preparations to prevent them from reaching the Gaza Strip," the spokeswoman told AFP.
On Thursday evening, Israeli warships came within six nautical miles of the two vessels, and Israeli spotter planes were observed overhead, said Fintan Lane, a coordinator of the Irish Ship to Gaza campaign.
But fears of an overnight boarding did not materialise.
Pro-Palestinian group International Solidarity Movement said that local fishermen and supporters had been expecting to welcome the ships into Gaza port at around 9:30 am (0730 GMT).
Activists organised a major attempt to break Israel's blockade in May 2010, when six ships led by the Turkish Mavi Marmara tried to reach Gaza.
Israeli commandos stormed the flotilla some 80 nautical miles off Gaza, in a botched raid which left nine Turkish activists dead and sparked a diplomatic crisis with Ankara, which expelled the Israeli ambassador and has cut military ties with the Jewish state.
Earlier this year, a second flotilla tried to reach Gaza, but several ships were sabotaged -- which activists blamed on Israel -- with only the Dignity attempting the last leg before being intercepted by the navy.
Organisers of the current flotilla, dubbed Freedom Waves to Gaza, said they had organised their effort in secret, in a bid to prevent Israeli interference.
Israel has vigorously defended its right to maintain a blockade on Gaza, saying it is necessary to prevent weapons from entering the coastal territory, which is run by the Islamist Hamas movement.