ISLAMABAD, Pakistan - Pakistan's army pushed deeper into a Taliban sanctuary close to the Afghan border Tuesday, killing 42 alleged militants in the latest stage of an offensive against extremists blamed for surging suicide attacks.

In the capital, gunmen attacked a high-ranking Pakistani army officer in the second targeted shooting against top military brass in less than a week, authorities said.

The officer escaped unhurt from the assault in Islamabad, part of a wave of violence sweeping the country in apparent retaliation for the 11-day long army offensive in South Waziristan in the northwestern border region.

The fight is seen as a major test of Pakistan's will and ability to tackle extremist strongholds in the northwest that have festered for years, largely untroubled by ground assault.

An army statement said troops were progressing well on three fronts in South Waziristan, but were meeting resistance.

It said over the last 24 hours, at least 42 militants and one solider had been killed.

Independent verification of army claims is very difficult because the military has blocked access to the region.