The Israeli military has defended its handling of clashes in Gaza which left 16 Palestinians dead even as footage emerged appearing to show unarmed protesters being shot by Israeli snipers.
Palestinian mourners called for "revenge" as they buried their dead after the bloodiest day in Gaza since the 2014 war and both side braced for what is expected to be weeks of rolling protests.
Around 30,000 Palestinians marched towards the Israeli border on Friday, where some hurled rocks and burning tyres and Israeli troops opened fire with live ammunition.
António Guterres, the UN secretary general, called for an investigation into the killings.
The Israeli Defence Forces (IDF) said that its forces had fired only at specific people who were deemed to be “violent instigators” in the demonstrations.
“The use of snipers was against specific people who were specific perpetrators of violence,” said Lt Col Peter Lerner, an IDF spokesman.
However, widely shared videos on social media appeared to show at least two unarmed men by Israel gunfire.
Three separate clips were published on social media purporting to show one Palestinian shot as he walked towards the border the Israel.
Using the three available videos of Incident 1 (east of Jabalia, #Gaza), I synchronised the footage of an apparent unarmed man that is walking towards the border fence and is being shot at. pic.twitter.com/eOgvQ6FLHz
— Christiaan Triebert (@trbrtc) March 31, 2018
Another clip showed a young man running away from Israeli positions holding a car tyre. Car tyres are sometimes set on fire by protesters and rolled towards Israeli forces.
In the clip he appears to be shot in the back and crumples to the ground. Palestinian media reported that the man, identified as 18-year-old Abed el-Fatah Abed e-Nabi, later died from his injuries
Lt Col Lerner said he could not comment on the specifics of the incident. “The fact that you have a video of 30 seconds showing this guy running away and being shot means you don’t see the context or what he was doing beforehand,” he said.
A second clip appears to shows an unidentified man, with no visible weapons, walking slowly towards the Israeli position when he was shot. It is not known if he was killed.
Hamas, the Islamist militant group that controls the Gaza Strip, said in a statement that five of the 16 people killed were members of its armed wing who were participating in the protests.
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The Israeli military released footage showing two men with assault rifles trying to break through the Israeli fence on Friday night. Both men were killed by fire from Israeli tanks. The UK, US and EU all consider Hamas to be a terrorist group.
A spokesman for Mr Guterres said the UN leader wanted “an independent and transparent investigation into these incidents.
“He also appeals to those concerned to refrain from any act that could lead to further casualties and in particular any measures that could place civilians in harm's way.”
The violence comes at the start of a tense period which will culminate in the opening of the controversial US embassy in Jerusalem in May and the 70th anniversary of what Palestinians call “The Nakba” - the mass displacement of Arabs during the 1948 war with Israel.
Friday’s demonstrations were billed as the start of the “Great March of Return”, in which Palestinian refugees will demand to be able to return to their 1948 homes in what is today Israel.
Palestinians have erected camp sites of tents at five locations along the Gaza border and plan to move the tents closer and closer to the border as the May 15 Nakba anniversary nears. The protests have been backed by Hamas.
Small demonstration continued on Saturday and there were reports of some injuries among Palestinians but no major confrontations are expected until next Friday.
The Israeli military tweeted early on Saturday its response was “accurate and measured, and we know where every bullet landed”.
When asked by reporters a spokesman could not say how many live rounds the Israeli military fired on Friday or how many people were shot. The military later deleted the tweet.
Related: Deadly clashes in the Middle East