Hamas said Monday it will delay the further release of hostages in the Gaza Strip after accusing Israel of violating a fragile ceasefire that now faces its most serious crisis since it began three weeks ago.

Hamas on Monday announced it would stop releasing Israeli hostages until further notice over what the Palestinian militant group called Israeli violations of a ceasefire agreement in Gaza, raising the risk of reigniting the conflict.

Stalling the next release of hostages from the Gaza Strip, scheduled for the coming weekend, raises new challenges for the already tenuous six-week truce and chances for a lasting end to the war.