KABUL, (Reuters) – An improvised explosive device (IED) killed four U.S.-led coalition soldiers on Saturday in the southern Afghan province of Kandahar, the scene of a large anti-Taliban offensive and an insurgent jail break.

Two coalition soldiers were also wounded in the blast, a U.S. military statement said, without giving further details.

The Taliban have upped pressure on Kandahar in the past two weeks, freeing at least 300 of their comrades in the jail break, then occupying areas outside the town, forcing Afghan and foreign troops to launch a large offensive to clear them out.

In another incident, an IED killed a Polish soldier from the NATO-led International Security Assistance Force (ISAF) and wounded four more on Saturday in the southeastern province of Paktika, the Polish news agency PAP said.

A suspected Taliban rocket also hit a hospital in the northeastern town of Asadabad close to the Pakistan border, killing one man and wounding another man and a woman, provincial Governor Sayed Fazlullah Wahidi told Reuters. He said the rocket appeared to have been fired from across the border inside Pakistan. Afghan officials often accuse Pakistan of aiding Taliban and al Qaeda militants who launch cross-border attacks into Afghanistan, charges Pakistan denies.

The Taliban have vowed to step up their campaign of suicide and roadside bombings this year to weaken the pro-Western Afghan government and wear down Western support for the continued presence of international troops inside the country.

While Afghan and international forces are able to fight off any conventional Taliban attack, combating suicide and roadside improvised explosive devices is proving more of a challenge as it depends on good policing and intelligence work.

As well as about 50,000 ISAF troops there are some 14,000 mainly American soldiers who are part of the U.S.-led coalition in Afghanistan, mainly involved in anti-terrorism operations and training Afghan security forces.

Elsewhere in Afghanistan, coalition forces launched airstrikes targeting a Taliban commander and a group of militants in eastern Khost province, bordering Pakistan.

Coalition troops also killed several militants and detained three more in the northeastern province of Kapisa, the U.S. military said on Saturday.

One coalition soldier was also killed and two wounded in the western Afghan province of Farah on Friday.

Afghan security forces, backed by coalition troops, killed several militants they had observed trying to plant a roadside bomb in the southern province of Helmand on Thursday, the U.S. military said on Saturday.