The KK Super Mart chain apologised after photos of the socks on sale caused widespread anger among Muslims.

The attack on Saturday came days after the KK Super Mart chain’s top executives were charged for hurting religious feelings because it sold the socks.

Wan Mohamad Zahari Wan Busu, the police chief in Kuantan city in Malaysia’s east, said the explosive device caused a small fire at the entrance of the store’s branch there, but no injuries were reported.

The attack was “still under investigation, but we’re not denying that it may be related to the incident involving stockings with the word ‘Allah’”, he told the AFP news agency.

Pictures of the socks spread on social media this month, prompting public anger among some Muslims who regarded them as insulting, especially because they went up for sale during the holy fasting month of Ramadan.

About two-thirds of the 34 million population is Malay Muslim, with large minorities of ethnic Chinese and people of Indian origin also practising Islam.

On Tuesday, a petrol bomb was thrown into a KK Super Mart outlet in Perak state, the Reuters news agency reported.

The chain’s founder Chai Kee Kan and his wife Loh Siew Mui, a company director, were on Tuesday formally charged with “deliberately intending to hurt … religious feelings”. Three representatives from KK Super Mart’s supplier, Xin Jian Chang, were also charged.

All the defendants pleaded not guilty. The chain’s executives were freed on bail, with a hearing set for April 29. If convicted, they could face up to a year in jail, a fine, or both.

Malaysia’s second-largest mini-market chain has previously apologised for the socks and said it had taken immediate action to stop their sale. It also sued the supplier of the socks, alleging sabotage and damage to its brand reputation.

The supplier said the “problematic socks were part of a larger shipment of 18,800 pairs ordered” from a company based in China.