Serbian authorities have put on display some of the 13,500 weapons they say people have handed in since this month’s mass shootings, including hand grenades, automatic weapons and anti-tank rocket launchers.

The authorities declared a one-month amnesty period for citizens to hand over unregistered weapons or face prison sentences as part of a crackdown on guns following the two mass shootings that left 17 people dead, many of them children.

Populist president Aleksandar Vucic accompanied top police officials on Sunday for the display of weapons near the town of Smederevo, some 30 miles south of the capital Belgrade.

Mr Vucic said approximately half of the weapons collected were illegal while the other half were registered weapons that citizens had nonetheless handed over.

He added that the weapons would go to Serbia’s arms and ammunitions factories for potential use by the armed forces.

“After June 8, the state will respond with repressive measures and punishments will be very strict,” Mr Vucic said of the post-amnesty period.

“What does anyone need an automatic weapon for? Or all these guns?”

Serbia is estimated to be among the top countries in Europe as regards guns per capita.

Many are left over from the wars of the 1990s and are held illegally.

Other anti-gun measures will include stricter controls of gun owners and shooting ranges.

Authorities launched the crackdown after a 13-year-old boy took his father’s gun and opened fire on fellow students at a primary school in central Belgrade on May 3.

A day later, a 20-year-old used an automatic weapon to shoot randomly in a rural area south of Belgrade.

The two mass shooting left 17 people dead and 21 wounded, stunning the nation and triggering calls for changes in the country which has been through decades of turmoil and crises.

Tens of thousands of people have rallied in two protest marches in Belgrade since the shootings, demanding resignations of government ministers and a ban on television stations that promote violent content and host war criminals and crime figures.

Mr Vucic rejected opposition calls for the resignation of interior minister Bratislav Gasic, who was also present at Sunday’s weapons display.

But the president suggested that the government might resign and that he would announce an early election at a rally he had planned for May 26 in Belgrade.

“We have no intention of replacing (interior minister) Gasic, who is doing a great job,” Mr Vucic said.

“What have police done wrong?”

Opposition politicians have accused Mr Vucic’s populist authorities of fuelling violence and hate speech against critics, spreading propaganda on mainstream media and imposing autocratic rule in all institutions, which they said stoked divisions in society.