The Straits Times confirmed that at least 12 schools, from primary to junior college levels, have raised prices in the past four months.

Five more schools are in discussions about increasing prices, while vendors at another five have shrunk portion sizes to get around the cost hikes.

Some of their young customers, finding their recess- time meals more expensive or less filling, are now taking food to school.

Most of such price increases, however, have been gentle. At Jurong Secondary, for instance, a bowl of noodles that used to cost $1.70 now goes for $1.80.

Vendors in the tuckshop at St Anthony's Canossian Primary have held prices steady, but pupils say the rice portions are now smaller.

Tuckshop food is cheaper than that in coffee shops. A bowl of noodles in a primary school goes for 70 cents, compared with $2.50 outside.

But these low prices are eating into vendors' incomes.

Madam Nancy Sit, 54, who runs the drinks stall at Northview Primary, makes 20 per cent less nowadays.

She said that seven litres of soya bean drink which used to cost her $2.50 now costs $4.50; the cost of essentials like sugar has also gone up.

'I can't change jobs because of my age, so I have no choice,' she said.

Tuckshop vendors, like restaurants and food courts here, have also been hit by the rising cost of items like rice, oil and flour. But many are hesitant about passing the increased cost to students.

Madam Poh Kwee Lay, 50, who sells rice with various meat and vegetable dishes in the tuckshop at St Patrick's Secondary, said: 'The students don't have much money either. How can I take it from them?'

She has not raised her prices, but said she now makes 'much less'. She now pays $80 for a 50kg bag of rice, up from $50.

The Ministry of Education (MOE) said it sets general policies on tuckshops, but leaves their running to the schools.

How vendors are chosen varies by school. Some schools put out a single tender so the contractor who wins it sublets the stalls; other schools invite individual vendors to bid for stalls.

Food prices are usually fixed at the contract stage; if vendors want to increase prices, they have to submit proposals justifying the move. Most schools set their prices at the start of the year and at mid-year, though prices can be revised at other times.

The principal of Tampines North Primary, Madam See Bee Huay, 41, said: 'The goal is to strike a fair deal...and not overburden the parents.'

The MOE provides a list of average prices to help schools determine a fair price vendors should charge.

Among students feeling the pinch is Ngee Ann Polytechnic student Kristle Chia, 21, who now takes her own food to school on some days.

'It's tearing a hole in my pocket. I have to go hungry sometimes,' said the third-year mass communication student. She said she used to spend only $4 on food, but now spends $6 - her entire daily allowance.

But some students think the price increases are acceptable. Yu Ying Secondary student Benjamin Leow, 15, said he 'didn't feel the pinch'.

Schools are prepared to aid students hard hit by these price rises. Meridian Junior College's vice-principal Pang Lay Har, 46, said: 'We'll judge on a case-by-case basis... We're prepared to let them eat for free, if necessary.'

She said the school will give goodwill coupons to students who need them most.

Schools can help their needy students by tapping into government schemes such as the Financial Assistance Scheme and Opportunity Funds as well as The Straits Times School Pocket Money Fund.

Stallholders, who bid for stalls individually at all government schools including autonomous schools, are charged a monthly rent of between $5 and $15, said the MOE.

neugene@sph.com.sg

ADDITIONAL REPORTING BY MALINI NATHAN, LIM POW HONG AND SUJITH KUMAR