Deep-seated anger and resentment are often at the root of why some children do not support their elderly parents, who have to haul them to court to get maintenance.

The parent may have abandoned, abused or neglected his children when they were young, Mr Khoo Oon Soo, Commissioner for the Maintenance of Parents (CMP), told The Sunday Times.

For instance, the parent could have been hooked on gambling, alcohol or other vices and failed to support his family. Or he could have been unfaithful, with another family on the side.

Mr Khoo said: "The children have harboured anger and resentment for many years. They feel that, since my dad walked out on the family, why should I support him now?"

Another reason for strained ties is that the child feels the parent has favoured another child, usually a son.

Mr Khoo said it is common to see seniors sell their flats and use the proceeds to help their sons buy a bigger house. But they are later asked, or choose, to leave their son's house when tensions arise.

So they turn to their other children for support. But the other children feel the son should take up that responsibility, since he had benefited from the sale of the parent's flat.

Mr Khoo said: "My advice to the elderly is: Never sell your flat. If anything happens, you still have a flat to fall back on."

The conflicts between daughters- or sons-in-law and the elderly are another reason why their children do not support them, Mr Khoo said.

According to the Ageing Families in Singapore report released last month by the Ministry of Social and Family Development, fewer parents are turning to the CMP in recent years. Last year, 213 seniors went to the CMP to seek maintenance from their children, down from 257 in 2013 and 303 in 2012.

One possibility behind the fall in numbers, Mr Khoo said, is because the Government's Social Service Offices (SSOs) are referring fewer seniors to the CMP.

Social workers explain that seniors who ask the SSO for financial aid are usually given short-term help. SSO staff will usually ask these elderly folk to explore the possibility of getting maintenance from their children through the CMP.

Social workers say most parents would not go to the CMP to get their child to support them, unless they have no other means of survival.

Many fear this would worsen - or even sever - their strained ties with their child. Already, most are not on talking terms and some have not had any contact with their children for decades.

Mrs Chua Yixin, senior social worker at Trans Safe Centre, said: "For Asians, they feel ashamed that their children are not supporting them. They don't want to wash their dirty linen in public."

Since 2011, seniors asking for maintenance have to go to the CMP, which is not a court setting, first for mediation.

"There are always two sides to a story and we will listen to both sides," Mr Khoo said. "We will mediate to try to get both sides to come to a sum they can agree on."

If this conciliatory approach fails, the parent can take the dispute to the Tribunal for the Maintenance of Parents (TMP), which is considered a court.

Eight in 10 cases are resolved successfully at the CMP, Mr Khoo said, and the children usually give between $100 and $300 a month.

Most of the parents come from low-income backgrounds, with close to half living in one- or two-room flats. On average, six in 10 who ask for maintenance are fathers.

While they may decide to give maintenance after mediation, most children do not reconcile with their parents, Mr Khoo noted.

One example of how a relationship can deteriorate relates to Mary, a 70-year-old divorcee who has four children in their 40s. She lives alone in a one-room rental flat and used to work as a part-time waitress, earning about $500 monthly.

"My children hate me. My ex-husband brainwashed them against me," she said. "He was always suspecting me of having boyfriends outside, which is not true."

Last year, she went to the CMP to ask for $100 from each of her children to help her with her living expenses. They refused. But she decided not to press the matter further, hoping to preserve their relationships. But the damage has been done. She said: "Now, they don't even want to talk to me or answer my calls."