SEOUL (AFP/Reuters) - North Korea test-fired seven missiles off its east coast Saturday, South Korean officials said, in what appeared to be a calculated message of defiance timed for the US Independence Day holiday. The launches fuelled regional tensions after the communist states nuclear test in May, which coincided with the US Memorial Day holiday. South Koreas Yonhap news agency said the missiles test-fired 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 UN 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 missiles in 2006 around the US July 4 Independence Day holiday, including its longest-range Taepodong-2. The launches came as the US 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 Norths 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. Todays missiles seem to have political purposes in that they were fired a day ahead of the US Independence Day, the agency quoted the official as saying. South Koreas Defence Ministry confirmed the North fired seven missiles off its east coast from morning to late afternoon that had a range of between 400 and 500 km but declined to say what type they were. Yonhap news agency said they were either Scuds, or Rodong-1 missiles whose maximum range of 1,300 km had been shortened. It is a provocative act that clearly violates UN Security Council resolutions, Yonhap quoted a statement from South Koreas Foreign Ministry as saying. Japans foreign ministry said in a statement the country: strongly protests and regrets todays missile launches by North Korea as they are a serious act of provocation against the security of neighbouring countries, including Japan. North Korea fired four short-range, non-ballistic missiles into the sea off its east coast on Thursday. North Korea fired a rocket it said put a satellite into space in April. US, South Korean and other officials said the launch was a disguised test of the long-range Taepodong-2 missile, which could hit U.S. territory, and nothing was put into orbit. The North has also threatened to fire another Taepodong-2, but there has been no indication it has started preparations of placing a rocket on a launch pad and fuelling it, a process that takes about four days and can be seen by US spy satellites, South Korean officials have said.