Sinwar, who was close to Hamas founder Sheikh Ahmed Yassin and was known for founding the internal security bodies of Hamas, was previously sentenced by Israel to four life terms in the late 1980s.
He served 23 years in the Israeli prisons.
In 2011, he was freed along with 1,047 Palestinian prisoners for Israeli soldier Gilad Shalit, who was abducted by Gaza fighters in a cross-boundary attack in 2006.
Sinwar returned to his position as a prominent leader in Hamas and was appointed head of the group’s operations inside the Gaza Strip in 2017.
The decision comes after Haniyeh was killed in Tehran on 31 July. Haniyeh had travelled to Iran to attend the swearing-in ceremony of Masoud Pezeshkian, the new Iranian president, and was staying at a residence where he was reportedly struck by a โprojectileโ.