The Israeli navy is preparing to intercept two ships carrying pro-Palestinian activists, including one Canadian vessel, sailing from Turkey to the Gaza Strip.

The navy has completed the necessary preparations to prevent them from reaching Gaza, it said in a statement.

The Canadian ship Tahrir and the Irish ship Saoirse are in international waters and about to head for Gaza, according to a statement from the Freedom Waves to Gaza campaign, which has organized the trip. It maintains that the blockade is illegal and prevents aid from reaching Gaza.

"We are now in international waters and hope to reach the shores of Gaza in a matter of days," said Canadian Boat to Gaza organizer Ehab Lotayef from on board the Tahrir.

"Among the significant obstacles in our way are Israel’s military and the complicity of the Harper government, but we have the wind of public opinion at our back and in our sails, which strengthens our resolve and determination to challenge the illegal blockade of Gaza’s 1.5 million inhabitants."

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The Israelis, however, say the ships' purpose "is to create a provocation against the State of Israel, to break the maritime security blockade on Gaza, and to undermine Israel's security," security officials said.

The two ships have 27 passengers from five countries on board, the CBC's Derek Stoffel reported from Jerusalem.

Not Canadian-registered

The Tahrir is not a Canadian-registered vessel, but is owned by the Canadian non-profit CBG and supported by donations, a spokeswoman told CBC News Wednesday.

"It is not registered in Canada, but we ask that the Canadian government protect Canadian citizens everywhere …," she said.

The Department of Foreign Affairs and International Trade renewed a caution Wednesday to Canadians against travel to Gaza, saying: "Canadians who break the laws of another country are subject to the judicial system of that country. DFAIT can neither offer protection from the consequences of such actions nor override the decisions of local authorities."

Foreign Affairs Minister John Baird said in a statement: "I strongly urge those wishing to deliver humanitarian goods to the Gaza Strip to do so through established channels. Unauthorized efforts to deliver aid are provocative and, ultimately, unhelpful to the people of Gaza."

Baird also recognized Israel's right to protect itself and its people from attacks by Hamas and other terrorist groups, including by preventing the smuggling of weapons.

Israel maintains that its maritime blockade is legal and that a committee appointed by the UN to examine the matter has agreed.

The flotilla organizers say the Tahrir will be delivering "much-needed medicines" and that its primary aim remains to help free Palestinians.

Earlier flotillas of this kind have met with strong Israeli opposition and disputes over whether the ships were carrying aid or weapons.

"This is a provocation in a long line of provocations," said Israeli army spokeswoman Lt. Col. Avital Leibovich, adding that the activists were "more than welcome" to send aid to Gaza by land.

A similar flotilla last year ended in bloodshed — nine Turkish pro-Palestinian activists were killed and 45 injured after Israeli soldiers boarded a Turkish vessel trying to break the blockade.

Israel imposed a sea blockade on Gaza in 2007 after Hamas militants seized control there.