Medical aid group Doctors Without Borders (Medecins Sans Frontieres - MSF) on Monday urged the EU to pressure Israel to grant unrestricted humanitarian access to Gaza – and stop what it described as the "slaughter" of Palestinians, in an open letter to the top officials of the bloc and its 27 member-states.

The open letter shared at a Brussels news conference called for an immediate end to the withholding of aid on security grounds, which MSF said amounted to "collective punishment – a war crime."

The group further called for steps to boost medical evacuations, saying around 13,000 people, including more than 4,500 children, were in urgent need.

"Our message to the leaders is simple. We urge you to use all political, economic, and diplomatic tools to exert real pressure on Israel to stop the carnage in Gaza and to allow unhindered humanitarian aid," MSF International's secretary general, Christopher Lockyear told reporters.

The EU has launched a review into whether Israel is complying with human rights principles laid out in its association agreement with the bloc.