The Israel Defence Forces have warned people in some towns in the Khan Younis area to evacuate their homes and head to shelters.
ADVERTISEMENTAs Israel intensifies its ground operation in Gaza, Former Prime Minister Ehud Olmert told Euronews that Hamas' underground command centre is based in Khan Yunis, a city in the southern Gaza Strip
He told our correspondent Shona Murray, "That's where the real headquarters of Hamas is.
"They have the leadership, they are hiding, they have the bunkers, they have the command positions, they have the launching pads."
Khan Younis is the largest city in southern Gaza and is where people fled after being told to evacuate the north. The Israel Defence Forces have warned people in some towns in the Khan Younis area to evacuate their homes and head to shelters.
The population of Khan Younis went from 400,000 residents to over a million when hundreds of thousands left the northern Gaza Strip.
Watch Sasha Vakulina's report in the media player above.