Using a simple trick of sticking double-sided adhesive tape on their palms, a trio from China stole more than $100,000 worth of chips from patrons at the casinos in Marina Bay Sands (MBS) and Resorts World Sentosa (RWS).

After their three-week theft spree, two of them - Zhou Haiming, 41, and Luo Jianguo, 37 - left for China but returned to Singapore 11 days later with the intention of lining their pockets again.

The pair were arrested while trying to enter the MBS casino. Several pieces of ready-cut double-sided tape were found on them.

Zhou and Luo were initially sentenced to 18 months' jail by a district court in May after each pleaded guilty to one count of criminal conspiracy to commit theft and one of removing criminal proceeds.

But yesterday, the High Court increased their respective sentences to two years' jail after an appeal by the prosecution.

The pair's appeals for lighter sentences were dismissed.

The third member of their team, Huang Xiaomei, remains at large.

The court heard that Zhou and Luo, who are from Jiangxi province in China, were told by a friend that he knew someone - Huang - who "earns a lot of money at the casino in Singapore". Huang later contacted Luo through messaging app WeChat.

Zhou and Luo arrived in Singapore on social visit passes on Sept 18 last year.

Three days later, they met Huang at the MBS casino, where she told them they could make money by stealing casino chips.

Back at her rented place, Huang taught them how to pick up chips using double-sided tape stuck on their palms.

Between Sept 21 and Oct 12 last year, the trio worked together, with one person "palming" the chips while the others distracted the dealer and the victim.

To avoid getting caught, they targeted patrons who placed large bets using a whole stack of chips.

The trio had a success rate of 95 per cent.

The thefts of $100,225 worth of chips, on 284 different occasions, were not detected. Neither were another 13 occasions of attempted theft.

They stole from more than 60 casino patrons.

Zhou and Luo gave Huang 20 per cent of the value of their loot.

When the duo returned to China on Oct 13 last year, Zhou had about $1,000 and 6,800 yuan (S$1,380) with him while Luo was carrying 4,500 yuan.

They returned to Singapore on Oct 24 and were arrested on the same day.

The prosecution argued in its appeal that 18 months was manifestly inadequate to signal to recruiters in foreign countries that Singapore is not a "soft target", and to reflect that the serial thefts were well- planned and skilfully executed .