President Lee Myung-bak on Wednesday warned North Korea against any attempt to sway the December presidential election and reaffirmed his pledge to sternly respond to its provocation.

Lee convened a top security meeting as North Korean fishing boats continued to violate the maritime border in the West Sea, raising concerns of a new naval clash.

On Friday, South Korean patrol vessels fired warning shots at six North Korean crab boats to force them back. Another fishing boat briefly crossed the Northern Limit Line Tuesday night, marking the seventh incursion this month.

“The government urges North Korea to immediately halt attempts to interfere with the presidential election, which have been sharply increasing recently,” presidential spokesperson Park Jeong-ha said in a statement.

Lee directed his aides to ensure a “solid security posture” ahead of the vote, Park added.

The session was attended by the unification and defense ministers, the first vice foreign minister, the head of the National Intelligence Service and the senior presidential security advisor.

They also welcomed Beijing’s decision to keep Chinese fishing vessels away from the scuffle-ridden waters, which was reached at a bilateral meeting between Korean Foreign Minister Kim Sung-hwan and his Chinese counterpart, Yang Jiechi, on the sidelines of the U.N. General Assembly on Monday in New York.

The North claimed the boats were owned by the Chinese and blasted the South for launching a “shooting rampage.”

None of the ships were hit by the shots during the Friday incident, which followed a round of broadcast warnings, the Defense Ministry reported. Other than some 100 North Korean vessels, about 300 Chinese boats were operating at the time during the peak crab season.

On Sept. 12, seven North Korean vessels crossed the line twice and backed away after warning signs from the South Korean Navy. Separate groups of two to three boats repeatedly turned up again on Sept. 14, 15, 20 and 22, according to the Joint Chiefs of Staff.

Seoul officials largely decipher the intrusions as Pyongyang’s attempt at influencing the crucial election by stirring tension and social instability.

The communist regime has set out propaganda campaigns in the past, which contained criticism or credits for candidates chiefly over their North Korean policy and visions for inter-Korean relations.

The NLL is close to Yeonpyeong Island, which the North bombarded with artillery in November 2010, killing four South Koreans. Months before that, the North torpedoed a South Korean warship in the nearby waters that claimed 46 lives. Similar bloody clashes took place in 1999, 2002 and 2009.

Meanwhile, Lee and the ministers expressed disappointment at the result of the North’s parliamentary meeting on Tuesday because “the outcome included no measures to improve the livelihoods of the North Korean people that the international community had anticipated,” the spokesman said.

The North’s Supreme People’s Assembly endorsed legislation to extend its compulsory education to 12 years from 11 years and minor personal reshuffles, the official Korean Central News Agency reported.

The session had gained traction as the rubber-stamp parliament usually gathers once a year. It triggered speculation over drastic economic guidelines such as for allowing farmers to sell a greater amount of surplus yield, ramping up output and controlling spiking food prices.

The young leader became chairman of the mighty National Defense Commission at an April meeting after taking power in December following the death of his father, Kim Jong-il.

In recent months, positive signs have been seeping out of the impoverished state. The Swiss-educated, 20-something leader’s recent public appearances and economic measures are seen as reflecting his openness to break up the regime’s long-held tradition of secrecy and push for a more market-oriented system.

By Shin Hyon-hee (heeshin@heraldcorp.com)