North Korea (searchwarned Tuesday that any economic blockade by the United States and its allies against the communist state could lead to a war that would include Japan.

The warning came as the United States, Japan and Australia, began cracking down on the North Korean trade in illicit drugs, weapons and counterfeit money -- believed to be key sources of hard currency for Pyongyang (search) to buttress its regime and its suspected nuclear weapons programs.

North Korea's main state-run newspaper Rodong Sinmun (searchon Tuesday charged that the United States is "laying an international siege to the North and putting a blockade against it as a premeditated scheme to start a new war on the Korean peninsula."

North Korea will take "physical retaliation," including "all means and methods an independent country can take," if it concludes that the recent moves by the allies violate its sovereignty, Rodong said in a commentary monitored by South Korean news agency Yonhap.

"There is no guarantee that this blockade will not lead to such a serious condition as a full-scale war," said Rodong. "If war breaks out between the North and the United States, it will not be limited to the Korean Peninsula but all the areas where aggressors are lurking will become our targets."

North Korea accused Japan of turning itself into the "base camp for U.S. aggression against Korea."

North Korea traditionally churns out sabre-rattling rhetoric when its relations with the outside world worsen.

Japan has been tightening safety and customs inspections of North Korean ships long suspected of smuggling missile parts and narcotics between the two countries. In the past week, they have detained one cargo ship and blocked another from docking for safety violations.

The move came after a North Korean defector told U.S. lawmakers last month that a North Korean ferry linking the two countries was used to smuggle missile parts.

Japan allows trade with North Korea on an informal basis, though the two countries have no diplomatic relations. Last year, 147 North Korean ships made over 1,300 port calls in Japan.

In a joint statement in Hawaii last week, U.S., Japanese and South Korean officials expressed concern about the North's narcotics trafficking and counterfeiting, and said they discussed cooperation to stop them.

In the past few days, both Japanese and South Korean officials have said that intensifying pressure on North Korea would force it to accept a U.S. offer for multilateral talks on halting its suspected nuclear weapons programs.

In April, Australian authorities raided a North Korean-owned ship and charged its crew with aiding and abetting the trafficking of heroin.

Tensions have increased since October, when U.S. officials said North Korea admitted having a covert nuclear program.

Separately, the mayor of Hiroshima has invited North Korean leader Kim Jong Il to attend this year's memorial of the 1945 atomic bombing in protest of Pyongyang's plans to pursue nuclear weapons.

The annual memorial honors those who died on Aug. 6, 1945, when the United States dropped an atomic bomb on the western Japanese city in the closing days of World War II. About 160,000 people were killed or injured in the attack.