An Israeli legal center said Thursday that authorities have begun deportation hearings for activists detained from the international Sumud aid flotilla bound for the blockaded Gaza Strip.

In a statement, Adala center said it received calls from participants reporting that immigration officials initiated hearings on their detention and deportation orders at Ashdod port shortly after Israeli naval forces attacked dozens of flotilla ships late Wednesday and early Thursday.

"These proceedings were initiated without prior notice to their lawyers and while denying participants access to legal counsel,” Adalah said.

It called the measure "a grave violation of due process and a denial of the participants’ fundamental rights,” saying that it would continue efforts to secure legal access and pursue legal action if necessary.

The Global Sumud Flotilla, an international aid convoy, said 443 activists from 47 countries were detained after their vessels were attacked by Israeli forces near Gaza’s coast.