Hong Kong authorities have rolled out a massive security operation as they brace for protests during a top Beijing official's visit to the semiautonomous Chinese city.

Thousands of police officers were deployed Tuesday as Zhang Dejiang began a three-day trip to Hong Kong.

Zhang is the chairman of the National People's Congress, China's parliament. He is the highest-ranking Communist Party official to come to Hong Kong since then-President Hu Jintao paid a visit in 2012.

Zhang arrived at Hong Kong's airport at midday, giving a short speech before departing by car.

Hong Kong has seen increasing discontent with Beijing's tightening grip on the former British colony, including pro-democracy street protests that gripped the city in late 2014.