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WASHINGTON, July 4 (Reuters) - The United States urged North Korea on Saturday not to "aggravate tensions" but did not confirm whether Pyongyang had launched a series of missiles.

"We are aware of possible missile launches by North Korea and are closely monitoring North Korea's activities and intentions," said U.S. State Department spokesman Karl Duckworth. "North Korea should refrain from actions that aggravate tensions and focus on denuclearization talks."

North Korea fired seven ballistic missiles Saturday, South Korea's Defense Ministry said, in an act of defiance that further raised regional tensions already high because of Pyongyang's May 25 nuclear test.

South Korea's Yonhap news agency said the missiles were "Scud-type," marking an escalation of recent sabre-rattling by the reclusive North, which has fired several non-ballistic, short-range missile since the May nuclear test.

North Korea is barred by U.N. resolutions from firing ballistic missile such as the Scud. A South Korean Defense Ministry official said more launches could come soon.

Duckworth said the isolated, communist state should carry out its commitments under a Sept. 19, 2005, multi-party deal in which North Korea agreed to abandon all its nuclear programs in exchange for economic and diplomatic benefits.

"This type of North Korean behavior is not helpful. What North Korea needs to do is to fulfill its international obligations and commitments," Duckworth said.

He said missile launches by North Korea would underscore the importance of fully implementing U.N. Security Council resolution 1718, passed after the North's first nuclear test in October 2006, and 1874, passed June 12 after its latest test.

Resolution 1874 bans the export of all weapons by North Korea, which Washington says will cut off a significant source of funds for Pyongyang. It also bans all financial transactions with North Korea that could contribute to its nuclear or ballistic missile programs. (Editing by Bill Trott)

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