BEIJING, Oct. 2 (Xinhua) -- China's capital has strengthened the cleaning work during the National Holiday, especially in its heart Tian'anmen Square, where trash is not allowed to stay on the ground for more than 20 minutes.

"Move the garbage in 20 minutes, increase mobile toilets, deodorize the toilets...," a series of measures have been taken to keep the Tian'anmen Square clean and tidy during the National Day holiday.

More than 500 sweepers have been working in two shifts to collect the garbage in the square round-the-clock. About 14 tons of garbage was collected on Monday, the first day of the week-long holiday.

More than 20,000 sanitation workers are mobilized in Beijing each day during the holiday, said an official of the Beijing Environment Bureau.

The company has strengthened the cleaning work in and around the square since September 26 to ensure a clear environment for tourists from home and abroad.

The 440,000-square-meter square -- about the size of 63 football fields, is among the world's biggest public squares and one of the most popular tourist destinations in Beijing.

About 120,000 tourists gathered at the square at dawn of Monday to watch hoisting of the national flag.