By Roger Hardy BBC Middle East analyst

The death of a well-known Palestinian militant, Raed Karmi, in an explosion in the West Bank, comes at a time of heightened tension between Israel and the Palestinians over a series of security measures ordered by the Israeli Prime Minister Ariel Sharon.

Israeli bulldozing in Gaza has left hundreds homeless

It makes the prospects for American-led peace efforts in the region look increasingly bleak.

Anthony Zinni, the American special envoy to the Middle East, left the region a week ago cautiously optimistic that progress was possible.

Since then, a series of rows has clouded the atmosphere.

Gaza destruction

Controversy still surrounds the Israeli army's demolition of dozens of houses in the Gaza Strip, after a Palestinian attack launched from Gaza into southern Israel last week.

It seems many of the houses were not empty - as the Israeli army has claimed - and that hundreds of Palestinians have been left homeless.

Then there is the continuing row over the arms shipment Israel intercepted in the Red Sea.

The Israeli charge that Yasser Arafat has been buying weapons from Iran has thrown the Palestinian leader onto the defensive.

The arms shipment row has weakened Arafat

His officials initially said three people had been arrested in connection with the affair, but now say only one is in detention.

It is the fallout from this affair which has the most potential to wreck the peace efforts of General Zinni - who is expected back in the region later in the month.

As long as no satisfactory explanation of the shipment is forthcoming from Mr Arafat, Ariel Sharon will feel he is justified in taking harsh security measures - and resisting efforts to revive serious political dialogue.