WASHINGTON, Oct 15: US warplanes conducted very heavy daylight strikes against troops and other Taliban targets on Monday as a fourth American aircraft carrier moved near striking range of Afghanistan, defence officials said.

“They (the attacks) were robust,” one of the officials said, adding that about 50 navy attack jets and as many as 10 heavy air force B-1 and B-52 bombers were used against 13 military targets - including troop concentrations of the Taliban - early in the second week of an air campaign.

The strikes appeared to be the heaviest daylight raids yet in a nine-day old bombing and missile campaign.

One of the defense officials said the carrier USS Theodore Roosevelt had headed south through the Red Sea toward the northern Indian Ocean after passing through the Suez Canal on Saturday. The carriers Carl Vinson, Independence and Kitty Hawk are already in the Gulf and Indian Ocean region near Afghanistan.

The official said it was not clear whether the Roosevelt would replace the Independence, which is overdue on an earlier schedule to return to the United States, or if the Independence would be kept on station for the immediate future.

The Roosevelt, Independence and Carl Vinson each carries about 75 attack and support aircraft.

The Kitty Hawk sailed from Japan last month without its aircraft wing and officials have confirmed it could be used as a base for raids by elite American Special Operations troops from the Indian Ocean south of Afghanistan.—Agencies