An armed group has said that four of its members were killed in an Israeli drone attack in Egypt's North Sinai region.
Egyptian security sources said earlier that four people were killed by a missile strike on Friday as they prepared to launch rockets at Israel.
"Our heroes became martyrs during their jihadi duties against the Jews in a rocket attack on occupied lands," Ansar Bayt al-Maqdis, the group, said in a posting on a website.
It was not clear how the group determined that its members were the target of the attack.
Five security sources told Reuters news agency the attack was carried out by Israel. But Egyptian armed forces officially denied that was the case and an Israeli army spokeswoman in Jerusalem declined to comment on the incident.
The two countries have cooperated in tackling armed groups in Sinai in the past. Ansar Bayt al-Maqdis criticised the Egyptian military for what it called its repeated cooperation with Israel.
The Egyptian military said two explosions took place at a site 3km west of the border and south of the city of Rafah on Friday afternoon.
The security sources in Sinai told Reuters an Israeli aircraft launched missiles, killing four, after discovering they had planned to fire rockets into Israel.
One source said the Israeli aircraft had observed the men preparing three rocket launch pads to hit Israel.
It launched a missile, killing two men, then killed another pair who stepped up to the pads after the first strike.
However, an Egyptian army spokesman denied in a subsequent statement any Israeli role in the incident.
The Egyptian army said on Wednesday it had killed 60 fighters in the Sinai Peninsula in the month since Mohamed Morsi was deposed as president.