Macau could slip into a budget deficit should the city's gambling revenue fall below 15 billion patacas a month, Chief Executive Sam Hou Fai said in a statement.

Gaming revenue in the city did not meet targets in the first quarter, Sam said in a statement released April 15.

Four-fifths of Macau's tax revenues come from gambling, according to the government statement.

"The imbalance in our fiscal structure is serious and we must maintain a strong sense of crisis awareness," Reuters reported separately, citing public broadcaster TDM.