Israeli warplanes have bombed smuggling tunnels near the Gaza Strip's border with Egypt, following an upsurge in fighting between Israel and Gaza militants.

Israel says it struck the tunnels Wednesday in response to a bomb attack on Tuesday that killed an Israeli soldier near the Gaza-Israel border. The airstrikes caused Palestinians in southern Gaza to flee their homes.

Gaza militants also fired a rocket into southern Israel Wednesday, causing no casualties. Hamas militants who control Gaza blame Israel for the fighting, the most serious since both sides declared unilateral cease-fires on January 18.

Israeli Defense Minister Ehud Barak canceled a planned visit to Washington on Thursday to deal with the situation.

U.N. humanitarian chief John Holmes urged Israel Tuesday to re-open its crossings with Gaza to allow humanitarian supplies into the impoverished territory.

Holmes says Gaza also needs reconstruction materials to help it rebuild after the destruction caused by Israel's 22-day offensive against Hamas that ended January 18. The fighting killed 1,300 Palestinians and 13 Israelis.

Also Wednesday, the head of the U.N.'s aid agency in the region, Karen AbuZayd, said it is still assessing the damage to the 50 U.N. facilities in Gaza damaged during the conflict.  She said her group will ask Israel for compensation.  

But she noted that in the past eight years, the U.N. agency has asked Israel for a total of $1 million for other damage to U.N. property, and has never been paid.

In another development, Israel's military says it has severely reprimanded an officer for distributing booklets during the offensive urging soldiers to show no mercy to enemies.

The military says the booklet was based on the writings of an ultranationalist rabbi identified with the Jewish settler movement in the West Bank. It says the chief military rabbi had not seen the booklet or authorized its distribution.

Israeli rights activists say the booklet could have incited soldiers to commit hate crimes. Israel's military says the booklet incident is an isolated case.

Some information for this report was provided by AP, Reuters and AFP