An Egyptian soldier has been killed and at least eight Palestinians hurt in clashes at the Egypt-Gaza border.
Egyptian security officials said the soldier was hit by Palestinian gunfire from across the border, during protests over a delayed aid convoy.
International activists have been trying to take 200 aid trucks into the blockaded Gaza Strip, but Egypt has refused some of the vehicles access.
Dozens of activists were hurt during protests over the convoy on Tuesday.
The violence broke out as hundreds of Palestinians began throwing stones across the border at Egyptian security forces, who fired back at the protesters.
The Islamist militant movement Hamas, which controls Gaza, had called the demonstration over the convoy.
But Hamas police later fired into the air to disperse the crowd, witnesses said.
The Egyptian soldier was apparently killed by gunfire from the Gazan side.
Egypt and Israel impose a strict blockade on the Gaza Strip, which Israel says is aimed at weakening Hamas.
The activists said 60 people were hurt in the clashes
The Viva Palestina aid convoy, carrying items ranging from heart monitors to clothing and dental equipment, is aiming to break the blockade.
A spokeswoman for the group of about 500 international activists said the Egyptians had gone back on an agreement to allow their 200 aid trucks to enter.
Alice Howard said Egypt had said that dozens of the trucks would have to enter via an Israeli-controlled checkpoint - which Viva Palestina believed meant the goods would never reach their destination.
She said she understood the reason was because of the nature of some of the goods.
Items other than basic foodstuffs and medicines, such as medical machinery, are subject to a stringent approvals procedure, usually negotiated by established international aid organisations with the Israeli authorities.
Some of the activists staged a sit-in at the port of Al-Arish, where the trucks are currently waiting, which was broken up by some 2,000 Egyptian riot police, Ms Howard said.
Many of those injured were "quite severely beaten, with head injuries", she said. A few were taken to hospital, but returned to the convoy on Wednesday morning.
Several Egyptian security forces were also reported to have been injured.
Television footage showed Egyptian riot police hitting the activists with batons. Some of the activists responded by throwing stones.
UK MP George Galloway, with the convoy, said: "It is completely unconscionable that 25% of our convoy should go to Israel and never arrive in Gaza."
The clashes follow an earlier row with the Egyptian authorities over what route the convoy should take to reach Egypt in the first place.
A demonstration has also been held in the Syrian capital, Damascus, against Egypt's treatment of the aid convoy.
A few hundred people took part in the protest organised by Hamas and other factions in Syria.