UNITED NATIONS, March 30 (Xinhua) -- United Nations Secretary-General Antonio Guterres on Friday called for an independent and transparent investigation into the violent clashes between Israeli security forces and Palestinian protesters in Gaza.

The UN chief also appealed 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, said Guterres' deputy spokesman Farhan Haq in a statement.

This tragedy underlines the urgency of revitalizing the peace process aimed at creating the conditions for a return to meaningful negotiations for a solution that will allow Palestinians and Israelis to live side by side peacefully and in security, said the UN chief.

At least 15 Palestinians were killed by Israeli soldiers on the border fence in Gaza and hundreds were injured in Friday's clashes.

Thousands of Palestinians on Friday started the first day of the Great March of Return, a month-long sit-in staged along the border fence between the Gaza Strip and Israel to demand the return of Palestinian refugees who were forced to leave their cities during the Arab-Israeli war in 1948.