Prime Minister Chung Sye-kyun called Sunday for "caution" in considering lifting greenbelt zones in the Seoul metropolitan area to address the country's housing supply shortage, warning they can't be restored once damaged.

The ruling Democratic Party and the government have been weighing the option of lifting the development restrictions on greenbelt zones, although activists and other opponents raised concerns over its environmental impact and claimed it should be mulled only as a "last resort."

"What is right is that we should take a very cautious approach. That is because the greenbelts cannot be restored once they are damaged," he said in an interview with the local broadcaster KBS.

The prime minister noted that the government has yet to finalize its decision on whether to lift the greenbelt-restrictions to secure more land for the construction of new homes in Seoul and in its surrounding areas.

"We are at a stage where we are reviewing all possibilities," Chung said.

"We will formulate and announce refined policy measures -- rather than measures hastily cobbled together -- at the earliest possible date," he added.

A senior official at the presidential office Cheong Wa Dae also said that a decision on the greenbelt issue has yet to be reached.

"We need to think more about the issue," the official told reporters. "Wouldn't we have to comprehensively weigh the efficacy and costs (associated with the lifting of restrictions on greenbelt zones)?"

Over the past week, senior public and ruling party officials, including Kim Sang-jo, presidential chief of staff for policy, have said that the government will mull lifting greenbelt restrictions.

Their remarks polarized the public as critics argue that there can be other alternatives to secure more construction space while keeping intact the greenbelt zones, which they call the "lungs" of the bustling city.

The premier said that it is "inappropriate" for policymakers to make a flurry of remarks on policy measures that are not finalized, while warning those remarks could confuse the public and give a "wrong signal" to the market.

Development restriction areas in Seoul reach about 150 square kilometers, or 25 percent of its total area.

The Seoul metropolitan government has long opposed the idea of easing restrictions on greenbelt areas, citing the need to protect the environment and avoid excessive expansion of the city.

Gyeonggi Province Gov. Lee Jae-myung, bandied about as a potential presidential contender for the ruling party, also voiced opposition to the lifting of greenbelt development restrictions, warning "losses will outweigh gains."

"There is a need to reconsider the idea of expanding home supplies by damaging greenbelt zones," Lee told Yonhap News Agency over the phone.

"We need to be cautious, because if we lift the restrictions on greenbelt zones in important swaths of land in southern Seoul, chances are high that they would become assets for real estate speculation," he added.

The ruling party and government have been agonizing over how to rein in the continued rise in home prices amid growing public anger at its plan to impose higher tax rates on multiple homeowners, which critics say would only lead to a further increase in housing rental costs. (Yonhap)