Pro-Palestinian activists from a Gaza-bound boat intercepted by the Israeli navy have accused troops of tasering them when they took over their vessel the Estelle their lawyer told AFP on Sunday.
The Israeli army immediately denied the claim.
"They used electric shocker devices to the extent of what we call 'electro torture' on some of the activists," lawyer Gaby Lasky told AFP, adding that at least one of them is an MP.
It was not immediately clear how many of the 30 activists and crew on board the Estelle were allegedly shot with the stun guns, which use an electrical charge to incapacitate a person.
But Israeli army spokeswoman Avital Leibovich denied that the soldiers had used "violence" in intercepting the vessel on Saturday.
"No force was used when taking over the ship," she told AFP.
There were five parliamentarians from Europe on board: Ricardo Sixto Iglesias from Spain, Sven Britton from Sweden, Aksel Hagen of Norway and Vangelis Diamandopoulos and Dimitris Kodelas from Greece.
Former Canadian lawmaker Jim Manly, who is in his late 70s, was also on board.
After leading the Estelle to the southern port in Ashdod, Israel had arrested three of its nationals who were on board for incitement. A judge extended their remand on Sunday by three days.
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A spokeswoman for Israel's population and immigration authority told AFP that 19 of the activists -- 11 Swedes, four Norwegians, two Finns, a Spaniard and a Canadian -- were being held at Givon prison in Ramle, near Tel Aviv.
Sabine Haddad said they were due to be taken before a judge in the next few days, ahead of their deportation.
Eight others -- an Italian, two Spaniards and five Greeks -- had waived their right to a hearing and were already on their way home, she said.
Saturday's takeover ended the latest attempt by pro-Palestinian activists to breach Israel's tight maritime embargo on Gaza which prohibits all naval traffic in and out of the coastal territory.
Organisers said the Estelle was carrying a shipment of humanitarian aid and 30 doves, which the passengers had been intending to release on arrival in Gaza.
But Leibovich said that the army found only wooden chairs, bathing suits, books, two wheelchairs and two sacks of concrete, as well as a number of balls.
"There was no humanitarian equipment on board," she said, "excepting maybe the wheelchairs."
"All the talk about humanitarian aid is a lie and a provocation."
In May 2010, pro-Palestinian activists tried to reach the Gaza Strip in a six-ship flotilla which was stormed by Israeli troops in a botched pre-dawn operation which left nine Turkish nationals dead, sparking a diplomatic crisis with Ankara.
Since then, there have been several other attempts to reach Gaza by boat, all of which have been stopped by Israel, although there has been no repeat of the bloodshed.
Israel says its blockade is necessary to prevent weapons from entering the coastal territory, which is run by the Islamist Hamas movement.