Schools in Pakistan's northwestern city of Peshawar re-opened Monday morning for the first time since a Taliban raid massacred 150 people, mainly children, with returning students expressing defiance tinged with apprehension.

The December 16 attack on the Army Public School in Peshawar by a group of gunmen and suicide bombers prompted a bout of national soul-searching even in a country used to high levels of militancy, with the government moving to scrap a moratorium on executions and establish military courts.

Across the country, schools had remained shut for an extended winter break as authorities beefed up security.

At least 20 soldiers were seen at the main entry point of the Army Public School, with an airport-style security gate installed at the front.

Elevated boundary walls with steel wire fencing have been put in place around Peshawar and in schools throughout the rest of the country.

For 16-year-old Shahrukh Khan, who was shot in both legs while pretending to play dead in his school's auditorium, going back was traumatic.

"I have lost 30 of my friends, how I will sit in the empty class, how I will look to their empty benches," he told AFP before the school reopened.

"My heart has been broken. All the class fellows I had, have died, now my heart does not want to attend school," he added.

Of the 150 victims killed in Pakistan's deadliest-ever attack, 134 were children.

Other students struck a defiant note.

"I am not scared, no force can stop me from going to attend my school, I will go and will tell the attackers, 'we are not afraid of you'," 16-year-old Zahid Ayub, who sustained minor wounds, told AFP.