High school students studying for university entrance exams are among more than 90 people murdered in two attacks in Afghanistan.

The first, on Tuesday night, killed nine police and 35 soldiers at checkpoints in the north of the country, said officials in Baghlan province.

Taliban spokesman Zabihullah Mujahid claimed responsibility for the attack, which targeted a military checkpoint and an adjacent police post.

Weeks of relative calm in the Afghan capital Kabul were then shattered on Wednesday when a suicide bomber attacked a school in the mainly Shia area of Dasht-i Barcha.

"At around 4pm a suicide attacker who had strapped explosives to his body detonated himself inside the Mawoud education centre," police spokesman Hashmat Stanikzai said.


Image: An Afghan man holds the body of his relative killed in the Kabul attack

The attack left 48 people dead and 67 wounded, said the health ministry.

"My brother has been injured, possibly killed, because he wasn't breathing when I took his bloodied body out of the bloody, burning classroom," a man named Assadullah told the AFP news agency.

The Taliban was quick to deny any part in the Kabul attack, which bears the hallmarks of Islamic State. The terror group has targeted Shia areas many times before but has not yet claimed responsibilty.

Image: Afghan police arrive at the site of the bombing

Afghanistan has seen a recent surge in violence, including a huge Taliban onslaught on the city of Ghazni that started late last week.

Around 100 members of the security forces have died, officials said, and there are fears at least as many civilians have also been killed.

Government forces, backed by US air strikes, now appear to have pushed fighters out of the eastern city.

Experts say the attack was a boost for the Taliban because it shows it can sustain an attack against a strategically important city just 90 miles from Kabul.

"What we've seen over the last few days is a microcosm of the war in Afghanistan - overmatched Afghan troops, emboldened Taliban fighters, and American forces that eventually come in to help bail the Afghans out," said analyst Michael Kugelman of the Wilson Center in Washington DC.

"What's crystal clear is that nearly four years after the Afghan security forces took over the war efforts, they're still woefully unprepared for the task despite very real improvements in capacities in recent years."