Transport Commissioner Rosanna Law on Monday said the new Tseung Kwan O-Lam Tin Tunnel is operating smoothly and successfully diverting traffic from the old Tseung Kwan O Tunnel.

The new tunnel, with a connecting bridge, officially opened on Sunday but experienced congestion due to a minor traffic accident.

On a radio programme, Law said traffic in the area was flowing at three times the usual speed on Monday morning, indicating reduced congestion.

But she said most drivers were still using the old tunnel and it would take some time for people to familiarise themselves with the new route.

"Some drivers misunderstood some road signs, and changed lanes when heading towards Kowloon East. But actually, two of the lanes can reach Kowloon East," Law said.

"So we've added a new road sign and double white lines overnight, to prevent people changing lanes when heading towards Kowloon East. From our observations [on Monday morning], we could see that the situation had already improved."

Sai Kung District Council chairman Francis Chau said he believes most motorists will continue to use the old tunnel and he expects only 20 to 30 percent of the traffic will switch to the new one.

Meanwhile, Kwun Tong District Council chairman Wilson Or said the government should continue to pay close attention to the traffic situation in Kowloon East, especially that in Kwun Tong.

"If there are problems with the arrangements of the Tseung Kwan O-Lam Tin Tunnel, leading to traffic accidents, it will hang up the traffic in Kwun Tong," Or said.