South Korea is in early consultations with the United Stats over its reported plans to redraw a maritime air defense zone in response to China's declaration of its own air zone in the East China Sea, a diplomatic source said Monday.

Beijing's announcement in late November has added to military tensions in Northeast Asia. Seoul is especially irked as China's new zone includes Ieodo, an underwater reef that is home to a South Korean ocean research station.

The Park Geun-hye administration is apparently planning to expand the Korea Air Defense Identification Zone (KADIZ), according to local news reports.

Speaking to reporters after a Washington forum, Ahn Ho-young, Seoul's ambassador to Washington, said the allies have exchanged views on China's move from the very outset. But he refused to comment on the KADIZ issue.

A diplomatic source later suggested Seoul is seeking Washington's understanding on its plans.

"South Korea and the U.S. have been in close consultations since China unilaterally drew its air defense identification zone and the KADIZ issue is being discussed in the same vein," the source said, requesting anonymity.

The U.S. position on South Korea's move remains unconfirmed.

"The issue is being discussed in the Pentagon," a Pentagon official told Yonhap News Agency. "I am not sure whether we have received South Korea's finalized plans."

The official pointed out South Korea has not made any formal announcement.

State Department spokeswoman Jen Psaki also said she is not aware of such media reports.

"Or I don't even know that they're reports or if there has been an announcement. I haven't seen any announcement, I guess I should say," she said at a press briefing.

Seoul is expected to make a formal decision on the issue after a visit by U.S. Vice President Joe Biden, who began a weeklong tour of Japan, China, and South Korea over the weekend, another source said.

The White House confirmed that Biden plans to raise the problem.

"While a number of issues will be raised in the discussions he'll have, given the increase in regional tensions, the ADIZ that China announced will be an issue the vice president will raise," White House Press Secretary Jay Carney said at a separate news briefing.

  "This is an opportunity for Vice President Biden to raise our concerns directly with policymakers in Beijing and to seek clarity regarding the Chinese intentions in making this move at this time," he added. "It is also an opportunity to confer with our allies Japan and the Republic of Korea, both of whom are directly affected by China's actions." (Yonhap News)