SEOUL (Reuters) – North Korea fired seven ballistic  missiles yesterday, South Korea’s defence ministry said, in  an act of defiance towards the United States on its  Independence Day that further stoked regional tensions.

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 25 nuclear test.

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

It was the biggest barrage of ballistic missiles the North  has fired since it launched seven, including its longest-range  Taepodong-2, in 2006 near the July 4 holiday.

The launches came as the United States has cracked down on  firms suspected of helping the North in its trade in arms and  missiles, which were subject to UN sanctions imposed after  the nuclear test and are a vital source of foreign currency for  the cash-short state.

An anonymous South Korean official quoted by Yonhap said  the launch may have been intended to send a message to  Washington, the North’s main foe who for years has been trying  to press Pyongyang to end its atomic ambitions and rein in  missiles that threaten US allies South Korea and Japan.

In Washington, a State Department spokesman urged North  Korea to avoid further stoking tensions.