Palestinian officials say Israeli naval forces have opened fire on several Palestinian fishing boats off the coast of the Gaza Strip. The authorities, speaking on condition of anonymity, said Israeli forces targeted Palestinian boats north of the Nuseirat refugee camp, which is located five kilometers (3.1 miles) northeast of the city of Dayr al-Balah, early on Sunday, Arabic-language Safa news agency reported. There were no immediate reports of casualties and the extent of damage caused in the attack. The development came only a day after Israeli gunships opened fire on Palestinian boats near the shores of the border city of Rafah. One boat caught fire and sank as a result but there were no reports of casualties in the attack. Around 4,000 fishermen work in Gaza, half of whom live below the poverty line. Israel had imposed a limit of three nautical miles on fishing in the waters off the Gaza shore until August 2014. Under a ceasefire agreement reached between Israelis and Palestinians following a deadly 50-day Israeli war in August 2014, Tel Aviv agreed to immediately expand the fishing zone off Gaza’s coast, allowing Palestinian fishermen to sail as far as six nautical miles off the shore. The agreement also stipulated that Israel would expand the area gradually up to 12 miles. Palestinian fishermen, however, say the Israeli navy opens fire on them before they reach the agreed limit. Over the past two years, Israeli forces have carried out about 150 attacks on Palestinian boats, arresting nearly two dozen fishermen and confiscating nine boats. The Gaza Strip has been under an Israeli blockade since June 2007. The blockade has caused a decline in the standards of living as well as unprecedented levels of unemployment and unrelenting poverty.