As the interdependence between this mainland city and Hong Kong grows, residents may soon be able to use public transportation, pay tolls or buy milk on either side of the border without cash but using a single plastic card.

Shenzhen recently introduced IC non-contact cards which allow people to pay for subway, public buses, taxi fares, highways and bridge tolls, as well as make purchases in some chain stores and public parks.

Hong Kong has a similar system.

Now, Shenzhen authorities have pledged to merge their system with Hong Hong's network by the end of the year.

The network, which is under construction, is expected to cover 80 per cent of the current local public transportation system this year.

"Since our IC card uses the same technique as that of the Hong Kong electronic traveling ticket, namely Octopus, it's easy to integrate the two networks so that the card holders can make full use of the transportation systems of Shenzhen or Hong Kong," said Huang Xiaoge, director of the settlement center of Shenzhen Public Transportation Group.

However, the governments of both sides have not worked out how to deal with the exchange rate between renminbi and the Hong Kong Dollar.

"Both Hong Kong and Shenzhen governments are willing to solve the problems. It's just a matter of time," Huang said.

Analysts have praised the move, saying it will allow the neighboring cities to integrate much faster.

Statistics from the Shenzhen Luohu checkpoint show the border was crossed 85 million times last year. That's about 230,000 crosses per day.

Residents in some cities of Guangdong Province, Beijing and Shanghai can visit Hong Kong and Macao without joining tour groups.

There were 220,000 such visits between July and the end of the year.

More tourists are expected this year as the Guangdong provincial government has announced that, starting in May, residents in all Guangdong cities will be allowed to travel to Hong Kong individually.

Editor: Catherine