Hamas abducted Israelis and foreigners during the group’s multipronged attack on the country on October 7.
“We have updated the families of 199 hostages,” military spokesperson Daniel Hagari told a media briefing on Monday.
“The efforts on the hostages are a top national priority. The army and Israel are working around the clock to bring them back.”
Israeli officials had previously estimated that 155 people were being held captive by the Palestinian armed group.
Hamas abducted Israelis and foreigners into Gaza during its October 7 attacks on Israel, the deadliest on the country in decades.
The multipronged attack, dubbed Operation Al-Aqsa Flood, killed more than 1,400 people, most of them civilians, and wounded about 3,500 others, according to Israeli officials.
Israel responded with intense air attacks on Gaza, levelling once densely populated neighbourhoods and imposing a total blockade on the enclave.
About 2,800 people have been killed and more than 10,000 injured in the besieged enclave and occupied West Bank, according to Palestinian officials. A further 1,000 people are believed to be trapped under the rubble of destroyed buildings.
Hamas on Sunday said that nine captives had been killed due to Israel’s bombardment in the past 24 hours, bringing the number of captives allegedly killed to 22.
The announcement came a day after the group said 13 captives had been killed by Israel’s strikes, which Israeli officials denied.
The latest claim of casualties could not be independently verified.
On Monday, the Reuters news agency cited two unnamed Egyptian security sources as saying that an agreement had been reached to open the Rafah crossing and allow much-needed aid into the enclave.
But Israeli Prime Minister Benjamin Netanyahu’s office denied that any ceasefire had been reached.
“There is currently no truce and humanitarian aid in Gaza in exchange for getting foreigners out,” it said in a statement.
United States President Joe Biden has stressed the need for humanitarian aid for Palestinians in calls with Netanyahu and Palestinian President Mahmoud Abbas.
Washington is also seeking to evacuate its citizens and has told people to get close to the crossing so they can leave.
There are 500-600 dual-citizen Palestinian-Americans in Gaza, according to US government estimates.
Biden has also urged Israel to follow the rules of war in its response to the Hamas attacks in contrast to earlier statements supporting Israel’s right to retaliate.
“The overwhelming majority of Palestinians had nothing to do with Hamas’s appalling attacks and are suffering as a result of them,” Biden said on Sunday.
Gaza on Monday entered its fifth consecutive day without electricity, pushing vital services, including healthcare, water supply and sanitation, to the brink of collapse.