CAIRO -- Police have arrested 26 Internet activists in the port of Alexandria, and 14 of them were jailed for more than two weeks for "threatening national security," a security official said on Thursday.

Around 30 young Egyptians who belong to the so-called "6 April" group on social networking site Facebook, a group which earlier this year called for a day of protests at rising prices, gathered in Alexandria on Wednesday.

"We were heading for Sidi Beshr beach but a policeman prevented us getting there because we had a large kite painted with the Egyptian flag and we were wearing T-shirts with 'April 6 Movement' on," said Mohammed Abdel Aziz.

He said that in the evening the group was walking along the seafront singing nationalist songs when police arrived and arrested 14 of them, he said.

The official confirmed the arrests and said another 12 were detained on Thursday.

The first 14 arrested have been jailed for 15 days under emergency laws for "threatening public security," the official said, while the others are still being questioned.

The arrests "indicate the security agencies are targeting 35 young men and women who are members of the 6th of April group and all attending a trip arranged by the group," the Arabic Network for Human Rights Information (ANHRI) said in a statement.

ANHRI tried to contact those detained "but all their mobile phones are turned off, which raises concerns, especially with the well-known practice of torture" where they are being held, it said.

Esra Abdel Fattah, the woman who set up the April 6 group in March calling for protests against price hikes, was detained at the time but freed after her mother made an appeal to Interior Minister Habib al-Adli.

Fattah, 27, was among several bloggers arrested ahead of what was supposed to be a nationwide protest on April 6.

Egyptian police took her from a Cairo coffee shop a week before the planned day of action. Her Facebook group had 64,000 members, but observation of the day of protest was sporadic.

Instead, protests focused on the Nile Delta city of Mahalla, where three people were killed by police after clashes erupted when demonstrators pulled down posters of President Hosni Mubarak.