Seven of those arrested were released later Wednesday by an Israeli court, while three were kept in custody, including the main suspect, who was charged, Israel's Shin Bet domestic security agency said.

Authorities did not explain why the announcement of the March 12 arrests was delayed for more than three weeks, though Israel often keeps such cases under a gag order while it investigates.

The announcement comes ahead of expected new mass protests along the Gaza Strip's border with Israel on Friday.

A protest by tens of thousands last Friday led to clashes in which Israeli forces killed 17 Palestinians and injured more than 1,400 others, the bloodiest day since a 2014 war. There were no casualties among Israelis.

Shin Bet announced the arrests in a statement, saying the 10 Palestinians from the city of Rafah in southern Gaza were on a boat outside a designated fishing zone off the blockaded enclave.

It alleged one of those arrested, fisherman Amin Juma, 24, has been involved in "terrorist activities" for militant group Islamic Jihad.

According to the statement, Islamic Jihad assigned him to gather information to prepare for an attack using a Kornet missile against an Israeli naval vessel.

It said the plan was to fire on an Israeli vessel and take hostages that could be used in a prisoner exchange.

Juma was charged on Wednesday.

Israeli Prime Minister Benjamin Netanyahu in a statement called the arrests "proof of the real intentions of terrorist organisations in Gaza".

Israel's use of live fire last week has come under criticism from rights groups, while the European Union and UN chief Antonio Guterres have called for an independent investigation.

Israel has defended its soldiers' actions, saying they opened fire only when necessary against those throwing stones and firebombs or rolling tyres at soldiers.

It said there were attempts to damage the fence and infiltrate Israel, while alleging there was also an attempted gun attack against soldiers along the border.

Palestinians say protesters were fired on while posing no threat to soldiers.