North Korea unleashed a torrent of insults at South Korea's new president on Tuesday in a first mention of Lee Myung-bak since he won a December election with a pledge to get tough on his communist neighbour.

In the last week the North has test-fired missiles, expelled South Korean officials working at a joint factory park in the North and threatened to reduce South Korea to ashes in a show of anger at Lee and the South's ally, the United States.

North Korea called Lee, who took office in February, a "political charlatan", an "absent minded traitor" and a "U.S. sycophant" in a commentary in the communist party Rodong Sinmun newspaper carried by its KCNA news agency.

Lee's government has told Pyongyang that if it wants to keep receiving aid, it should improve human rights, abide by an international nuclear deal and start returning the more than 1,000 Southerners kidnapped or held since the 1950-53 Korean War.

The stand has infuriated the testy North, used to billions of dollars of aid over the past 10 years from Lee's left-of-centre predecessors whose "sunshine policy" sought little in return.

"The Lee Myung-bak regime will be held totally responsible for ushering in a catastrophic incident by freezing North-South relations and destroying peace and stability on the Korean peninsula through its pro-U.S., anti-North Korea confrontational attempts," the commentary said.

DEFLECT BLAME

With its taunts, analysts said the North may be trying to deflect blame from itself for a delay in implementing a deal with regional powers to scrap a nuclear arms programme in exchange for massive aid and an end to its international ostracism.

The North failed to meet an end-of-2007 deadline in a six-country deal to release a complete accounting of its nuclear material and weaponry, as well as answer U.S. suspicions of having a secret programme to enrich uranium for weapons.

The deal is what the international community hopes will eventually lead to a complete nuclear disarming of the North.

"The North has shifted to blaming the South for what it has not been able to work out with the U.S.," said Choi Jin-wook, an expert on the North at the South's Korea Institute for National Unification.

Lee's government has said it would work closely with the United States and Japan, and its stance on North Korea puts South Korea closer to its traditional allies in trying to exert pressure on the North to force change.

The chief U.S. envoy to the North Korean nuclear talks is scheduled to arrive in Seoul later on Tuesday.

Lee has proposed an aid package for North Korea that would lift per capita income from a few hundred dollars a year to $3,000, provided it abides by the six-way nuclear deal.

The North called Lee's plan "piffle" and said it "will be able to live as well as it wishes without any help from the South as it did in the past".

Analysts said that China, the closest the North has to a major ally, would lean on the hermit state to prevent the situation on the Korean peninsula spinning out of control.

Beijing, already facing criticism for its handling of the crises in Tibet and Sudan, does not want North Korea to be another headache and spoil its hosting of the 2008 Summer Olympics, they said.