A Singaporean woman whose husband and son are facing murder charges in Malaysia for allegedly killing a robber who slashed her has bemoaned the lack of justice.

Madam Kuek Soo Lan, whose left arm was injured in the attack and required 25 stitches, insisted that her Malaysian husband Moo He Hong, 57, and son Moo Wee Keong, 29, did not kill Chan Boon Poh, Nanyang Siang Pau newspaper reported.

The father and son pleaded not guilty to murder charges in court on Tuesday.

Speaking to reporters outside the court, Madam Kuek claimed that her husband and son only pinned down the man and he was still conscious and able to talk before she and her husband left the house to go to the hospital.

She said her husband only found out that the man had died when he went back home about 15 minutes later to get his handphone to take pictures of her injuries for insurance claims.

"I was being robbed and my husband and son tried to protect me, but they ended up being charged for murder. Where's the justice in this?" she was cited as saying by the Chinese-language newspaper.

Guang Ming Daily reported that Madam Kuek was unhappy with the murder charges and kept repeating the Chinese words "mei you tian li", which means "no justice".

The incident happened on Feb 24 when Madam Kuek and her family were visiting her husband's family in Negeri Sembilan over the Chinese New Year holidays. Her family live in Singapore, and they also have a daughter.

Madam Kuek said she was confronted by a masked man just as she was stepping into the house that night, after going out to buy supper with her husband.

"He dashed over to snatch my bag and I tried to resist, screaming for my husband to come and help," she said. She believed that her actions provoked the man who then slashed her with a knife.

Madam Kuek said her husband picked up a water pipe and fought with the man, and neighbours also helped subdue him. She added that her son, who was already asleep, was awoken by her cries and came out to help.

The attacker was subsequently found dead, lying on the ground with his hands and legs tied up with rope. It is not clear how he died.

The police who were called to the scene found a 45cm-long parang, two stones and broken pieces of a plastic water pipe.

The case will be heard again on April 30, according to media reports. Mo and his son could be sentenced to death if found guilty.