Shenyang, the capital city of Liaoning province, saw heavy smog between 6-7 am on Sunday. [Photo/Xinhua]

Heavy smog disrupted air traffic while snow and rain disrupted railways and highways in Northeast China's Liaoning province, Xinhua reported.

Liaoning provincial meteorological bureau Sunday issued an orange alert on heavy smog in most cities.

On Saturday, 15 flights landed at other airports, 12 returned and 236 flights were canceled by 9 pm in its port city, Dalian, affecting more than 7,000 passengers, the Dalian International Airport said in a statement.

Meanwhile, dozens of trains were delayed and highways were closed across Liaoning province on Saturday. Ice formed on some sections of the Beijing-Harbin railway, the Harbin-Dalian high-speed railway and the Panjin-Yingkou high-speed railway in Liaoning province, said an official of Shenyang Railway Bureau, based in the capital.

Emergency measures were activated to remove ice and speed limits were imposed.

Five expressway routes in Liaoning were completely closed and 10 others partially shut due to snow, which began on Friday afternoon.