HONG KONG (Reuters) - The chairman and president of the American Chamber of Commerce (AmCham) in Hong Kong were separately denied entry to the neighboring Chinese-ruled city of Macau on Saturday after being detained by immigration officials.

Chairman Robert Grieves and President Tara Joseph were traveling to the former Portuguese colony of Macau for the annual AmCham Macau Ball and said authorities did not provide a reason for refusing to allow them entry.

“We hope that this is just an over reaction to current events and that international business can constructively forge ahead,” they said in a statement.

The pair were told to sign a statement saying that they “voluntarily agreed not to pursue entry to Macau.”

Macau immigration authorities could not be reached for comment outside of business hours.

Joseph told Reuters she was puzzled as to why she was prevented from crossing into the gambling hub for the annual event which is also attended by the U.S. Consul General of Hong Kong and Macau, Hanscom Smith.

“I have no idea. I was quite surprised. They were not rude. There was never any manhandling or rudeness,” she said.

In November, U.S. President Donald Trump signed into law congressional legislation backing pro-democracy protesters in Hong Kong despite angry objections from Beijing.

The former British colony has been rocked by six months of often violent anti-government protests that have plunged the city into political crisis and pose the greatest popular challenge to Chinese President Xi Jinping since he took power.

Beijing has condemned the unrest and blamed foreign governments, including the United States and Britain, of interfering in the country’s internal affairs.