Foreign Secretary James Cleverly has condemned “horrific” attacks by Palestinian militants from the Gaza Strip in southern Israel.
Militant group Hamas has sent fighters across the border and fired thousands of rockets in what it said was a new operation.
Israel’s prime minister Benjamin Netanyahu said the country was “at war” as its military began striking targets in Gaza in response.
“The UK will always support Israel’s right to defend itself.”
Labour leader Sir Keir Starmer said: “I utterly condemn the ongoing attacks on Israel and her citizens.
“There is no justification for this act of terror which is being perpetrated by those who seek to undermine any chance for future peace in the region.
“Israel has a right to defend herself.”
Israel has blockaded Gaza since Islamic militant group Hamas gained control of the territory in 2007 and the two have fought wars ever since.