At least four persons were killed and more than 500 others were injured after an explosion at Iran’s largest commercial port, Bandar Abbas, on Saturday, reported the Associated Press.

The blast occurred at the Shahid Rajaee section of the port, located in southern Iran, more than 1,000 km from the capital Tehran.

An unidentified government official told Reuters that the exact reason for the explosion was yet to be ascertained, but chemicals are likely to have caused it.

Hossein Zafari, a spokesperson for Iran’s crisis management organisation, said that the blast was the result of poor storage of chemicals in containers.

“Previously, the Director General of Crisis Management had given warnings to this port during their visits and had pointed out the possibility of danger,” Zafari was quoted as saying by the news agency.

The explosion came against the backdrop of Iran and the United States holding negotiations regarding Tehran’s rapidly advancing nuclear program.

On Wednesday, Iranian Foreign Minister Abbas Araghchi, who is leading the talks, said that his country’s “security services are on high alert given past instances of attempted sabotage and assassination operations designed to provoke a legitimate response”.