BEIJING - Beijing issued an orange alert for heavy air pollution on Saturday morning as a round of smog started hitting the city at the weekend, local authorities have said.

The air pollution is to last from Saturday to Monday, said Beijing's air pollution emergency response office.

A series of measures will be taken from Saturday, including the suspension of a number of outdoor construction operations, the restriction of heavy-polluting vehicles, and the halting of production or restriction of some manufacturing companies, according to the municipal air pollution emergency response office.

An orange alert is issued when the air quality index surpasses 200 for three consecutive days.

The air quality is expected to get better on Tuesday.

Under Beijing's current air pollution warning system, yellow alert is the least severe, followed by orange and red.