By Karen Lema

MANILA (Reuters) - Philippine police said on Thursday they had arrested 43 foreigners for kidnapping a Singaporean woman at a casino resort in the capital, highlighting security concerns that have scared high-stakes gamblers away from Manila.

Police said the gang, including people from China and Southeast Asia, was believed to be a loan-shark syndicate targeting foreign high-rollers, with 11 similar cases reported since 2015.

The Philippines is one of the fastest-growing casino hubs in Asia, after Macau and Singapore, with the opening of several resorts over the past two years.

But security remains a major concern that has deterred big-spending gamblers from China, wary about kidnapping and extortion.

The 48-year-old Singaporean woman was losing heavily when she was approached and befriended by three men and a woman at the Solaire casino on July 17 who lent her money, police said.

They later invited the woman to another casino but she was instead taken to a hotel where she was mistreated and video of her was taken which her captors showed to her family with a demand for $180,000 for her release.

National police chief Ronald dela Rosa said the woman was rescued the next day.

Kidnapping complaints had been filed against two Malaysians and 41 Chinese nationals in connection with the case, de la Rosa said.

Solaire, which is owned by Bloomberry Resorts Corp, said it did not tolerate loan sharks and was coordinating with and supporting authorities in the fight against crime.

"Solaire continues to closely safeguard all its patrons to ensure their safety from unscrupulous personalities and activities," it said in a statement.

Last month, a gunman who police said had gambling debts stormed Manila's Resorts World casino, and set a fire in which 37 people were killed.

The kidnapping of the woman from Singapore would likely compound fears about safety in the Philippines, an analyst said.

"This incident will make it even harder for the operators to entice the high-rollers to visit," said Shaun McCamley, a partner at Global Market Advisors based in Bangkok.

The Philippines targets gross gaming revenue of 155 billion to 160 billion pesos ($3.1 billion to $3.2 billion) this year, up 4 percent to 7 percent from last year, data showed.

(Reporting by Karen Lema; Additional reporting by Manuel Mogato in MANILA and Farah Master in HONG KONG; Editing by Raju Gopalakrishnan, Robert Birsel)