Israeli forces have shot dead four Palestinians, including a 15-year-old boy, as more than 10 000 gathered in a mass demonstration in the besieged Gaza Strip demanding the right of return for Palestinian refugees.The Palestinian Ministry of Health said on Friday that at least 729 people protesting near the border with Israel were wounded by Israeli gunfire, needed treatment for tear gas inhalation or suffered other injuries.Palestinian officials identified those killed as Mohammed Ibrahim Ayyoub, 15, Ahmed Rashad, 24, Ahmed Abu Aqil, 25 and Saad Abdul Majid Abdul-Aal Abu Taha, 29.Friday's demonstration was the fourth in as many weeks of a planned, weeks-long sit-in dubbed the Great March of Return.The latest deaths bring the number of Palestinians killed by Israel since the protests began in late March to 39. According to the health ministry more than 4 000 have been wounded.Despite international criticism over the use of lethal force, Israel has refused to reverse its open-fire policy and continues to deploy snipers along the border. Al Jazeera's Bernard Smith, reporting from the protest, said the Palestinians seemed determined to edge closer to the border."The Palestinians are 300 metres closer to the Israeli border than they were last week because this protest is about a key issue - the right of return."The main message of the Great March of Return, which is due to continue until May 15, is to call for the right of return for Palestinian refugees who were driven from their homes in the territories taken over by Israel during the 1948 war, known to Arabs as the Nakba."What the protesters are planning is that by the final week, on the day of the Nakba, they'll be at the border fence with Israel," said Smith."And that's what the Israelis fear. They don't want them getting anywhere close to the border."The mass marches, which have been backed by several Palestinian factions, are also fuelled by growing desperation among Gaza's two million residents.The border blockade has trapped nearly all of them, gutted the economy and deepened poverty. Gaza residents typically get fewer than five hours of electricity per day, while unemployment has soared above 40 percent.Mahjoob Zweiri, an associate professor in contemporary history of the Middle East at Qatar University, told Al Jazeera that the Israelis feared the independent "discourse of the protest movement"."This is a movement created by the people who have lost faith in the Palestinian leadership - for that reason Israel is very fearful of them."The Israelis pushed the Egyptians to mediate, but the movement was disinterested, and so for this reason, they could continue using live ammunition against them until they stop." Journalists woundedAccording to The Committee to Protect Journalists, Israeli forces wounded four journalists covering Friday's protests.The group said Mohammad al-Sawalhi, a cameraman for the Gaza Media Center, was injured by a live round in his right hand in Gaza City's eastern neighbourhood of Shujaiya.Two weeks ago, photographer Yaser Murtaja died after being shot in the stomach despite wearing a blue flak jacket marked with the word "press".Asaad Abu Shariek, a spokesman for the Great March of Return, said the movement was hoping the large turnout would sway international opinion against Israel."We are implanting an idea in the minds of people across the world that Palestinians have rights and they hope for the right of return," Abu Shariek said."We want the world to impose a military embargo on Israel and the BDS [Boycott, Divestment, Sanctions] strategy. South Africa used this method [against apartheid], and they emerged victorious, and I think we will be no exception."Yahya Sinwar, Hamas' Gaza chief, told a protesting crowd near the Israeli border that they would "march on Jerusalem"."We will not bargain on the Palestinian people's rights in exchange for bread," he said.Palestinians have long demanded that as many as five million direct descendants of the original Palestinian refugees be given the right to return to their ancestral homes.Israel has ruled out the demand, arguing that the return of Palestinians to what is now Israel would outnumber its Jewish majority.