The bus routes have been the subject of a torrent of complaints from angry commuters who say traffic into the city has become noticeably worse.

However police said they will be watching closely for drivers who misuse them and will issue fixed penalty notices to offenders.

They also said red surface markings will be painted to highlight the fact that lanes are only for public transport usage.

"The misuse of a bus lane will result in the issuing of a £30 Fixed Penalty Notice," the PSNI said, in a statement to UTV.

The Police Service regularly issues Fixed Penalty Notices for misuse of bus lanes and police will react to reports of such abuses when observed.

PSNI

"However, Police are aware of the new bus lanes which will come into effect today and Officers in the city centre will monitor any abuse of these lanes. In the near future the bus lanes will be marked in red surface dressing to highlight their existence."

The addition of the lanes has led to many people finding themselves stuck in heavy congestion on their commute to and from work.

UTV spoke to some disgruntled drivers stuck in traffic on their way to work on Wednesday morning.

"Absolutely terrible", "horrendous" and "disruptive" were some of the terms used to describe their journey.

"I can't believe (the roads) they're so bad, it's taken me half an hour to go 200 yards," one driver said.

However there were a few travellers who were more tolerant of the initial problems, that said the introduction of the lanes were a good idea.

"The amount of traffic that's on the road is probably a bit congested at times, so hopefully the bus lanes might improve (it) so we can actually use the buses," one commuter said.

Responding to complaints of traffic backlogs in the city centre on Tuesday, Regional Development Minister Danny Kennedy said that there would be a "smoothing out period".

The clear message is that if you're simply travelling through Belfast by car to another destination, then you would be better to find an alternative route to allow the system of public transport to work effectively and properly.

Danny Kennedy

Mr Kennedy was speaking following the launch of an additional fleet of 145 new buses for Translink.

"My key objective in investing in public transport is to encourage commuters and other travellers to use public transport for their journeys instead of the private car and to travel more sustainably," he explained.

"There has also been good news with the latest passenger charter results showing customer satisfaction levels for Ulsterbus at an all-time high.

"Also, the programme to implement further bus priority measures continues within my department to help tackle congestion issues impacting on bus speeds."

He said the changes were an attempt to "transform the travelling habits of people, particularly in Belfast".

"A high percentage of the traffic that comes through Belfast doesn't actually stop in it, so we need to change the ethos, we need to give priority to public transport to make it more accessible, the new buses help with that as well," the Minister said.

"All in all it is a policy that we believe in and we think it worth pursuing in the better interests of the travelling public, particularly for those who will want to use public transport in increased numbers."