Israeli President Isaac Herzog has suggested his country is ready for another humanitarian pause in the fighting with Hamas, which still has about 130 hostages in Gaza.

The Israeli military is stepping up its offensive in the Gaza Strip, sending new troops to the major southern city of Khan Younis.

Reuters news agency reported fierce gun battles between Hamas fighters and Israeli forces in the city's central district on Wednesday.

Health authorities in Gaza say the death toll in the enclave since the start of the fighting has reached 19,667.

Herzog said during a meeting with foreign ambassadors on Tuesday that Israel is ready to negotiate another humanitarian pause to enable the release of the remaining hostages.

It has been reported that the head of Israel's Mossad spy agency met with Qatari mediators in Warsaw, Poland, on Monday.

The US news website Axios on Tuesday quoted Israeli officials as saying the Mossad chief proposed a pause of at least one week in exchange for the release of about 40 hostages.

Reuters quoted a source who was briefed on the diplomatic efforts as saying the talks were constructive, but a deal was not expected imminently.