The New Zealand retailer Gun City, which sold weapons to the man accused of shootings at two Christchurch mosques that killed 51 people and injured dozens, has sparked concern with plans for a megastore in the South Island city, according to media reports.

Radio New Zealand said some residents living near the proposed site were upset at the prospect of the 300 sq metres (3,229 sq ft) store, which opens in August.

“I don’t think many people will be very comfortable to have guns around their homes in a residential area,” said one of the residents, Harry Singh.

Gun City did not immediately reply to a request for comment.

The location is just over half a mile from the racetrack where New Zealand held its first firearms buyback on Saturday, four months after the country’s worst peacetime mass shooting.

The accused gunman bought four weapons and ammunition between December 2017 and March 2018, the Gun City owner, David Tipple, said in March. There is no suggestion there was anything improper about the sale.

Brenton Tarrant, who is to stand trial in May, has pleaded not guilty to 92 charges related to the attacks, including New Zealand’s first terrorism charge.

Tipple told Radio New Zealand he was sorry some people were concerned about the new store, but the chain was “willing and happy to introduce those persons to the positives of firearms”.

A gun reform law passed in April bars the circulation and use of most semi-automatic weapons, parts to convert firearms into semi-automatics, magazines over a certain capacity and some shotguns.

The government has allotted NZ$208m (£112m) for buybacks nationwide to compensate gunowners who surrender banned weapons. Police took in 224 firearms on Saturday, with 22 similar events scheduled this week.

With a population of just under 5 million and an estimated 1.5m firearms, New Zealand ranks 17th in the world civilian gun ownership per capita, the Small Arms Survey shows.