Israeli tanks entered the eastern area of the Gaza Strip today, and troops clashed with Palestinian fighters there, Palestinian sources said.
The Israeli army said it was checking the report.
Witnesses said several Israeli tanks, supported by unmanned drones in the sky, entered Gaza near the Karni crossing, the main terminal for goods entering and leaving the densely populated strip.
Clashes ensued and three militants were wounded, Palestinian sources said.
Israel has made repeated brief incursions into Gaza over the past six weeks, since launching an operation in late June to rescue a soldier captured by Palestinian militants and to stop rocket fire from the strip into Israel.
Earlier separate Israeli air strikes targeted houses in Jabalya, a district of Gaza City, in the northern part of the strip, and the southern Gaza town of Rafah, but there were no immediate reports of any casualties or damage.
Witnesses said residents had been warned to leave the buildings ahead of the strikes, which they said appeared to target the homes of members of the militant groups Hamas and Islamic Jihad.