The Israeli military said on Thursday that the number of people confirmed held hostage in the Gaza Strip since the Oct 7 cross-border raids by Hamas had reached 224, and could rise further.
Foreigners are among those captured by Hamas.
Four hostages have been released.
US President Joe Biden and Israel's Prime Minister Benjamin Netanyahu on Wednesday discussed "ongoing efforts to locate and secure the release" of Americans believed held hostage in Gaza, the White House said.
Biden also stressed to Netanyahu the "importance of focusing on what comes after this crisis to include a pathway for a permanent peace between Israelis and Palestinians," the White House said.