Prime Minister Ehud Olmert said on Monday that Israel would maintain the tighter blockade that it has imposed on the Gaza Strip since last month.

"We will continue to apply sanctions that are hurtful to the needs of the (Palestinian) population in order for it to be clear that living conditions cannot be altered only from our side," he told the parliamentary group of his Kadima party in allusion to near daily rocket fire from Gaza.

"Hamas bears responsibility for everything that goes on in the Gaza Strip, and it matters little whether it is or is not directly responsible for any given incident," army radio quoted him as telling the MPs.

Military sources said four rockets were fired on Israel on Monday, without causing any casualties.

Olmert was speaking just two days after French Foreign Minister Bernard Kouchner urged Israel to lift the blockade, saying the situation in the impoverished territory was "intolerable."

But Kouchner, on a visit to the region, also urged a halt to the rocket fire in order to avoid such "brutal" responses and said the creation of a Palestinian state was vital for Israel's security.

In response to the rocket fire, Israel has kept Gaza under effective lockdown since last June following the territory's takeover by the Islamist movement Hamas. On January 17 it tightened the blockade before easing it again slightly.

Olmert is expected to meet again this week with Palestinian president Mahmud Abbas in their latest round of peace talks, renewed in November after a seven-year hiatus.

Abbas has also demanded that the blockade be lifted, saying it is "not the people who are firing these rockets."