A group of South Korean lawmakers demanded tougher punishment for illegal Chinese fishermen as the country Wednesday mourned a coastguard officer killed while trying to arrest an offender.

The officer was fatally stabbed and a colleague wounded as they attempted Monday to detain the skipper of a Chinese boat in the rich fishing grounds of the Yellow Sea.

The incident -- the second time since 2008 that a coastguard officer had been killed in a Chinese attack -- has sparked widespread anger.

Twenty lawmakers of the ruling Grand National Party signed a resolution urging Beijing to crack down on illegal fishing and calling on Seoul to impose tougher punishment on offenders.

"The Chinese government should offer a responsible apology and vow to prevent a recurrence so that a sacrifice like this... would never be made again," lead signatory Chung Ok-Nim said in the resolution released Wednesday.

Two coastguard officers have been killed and 28 injured during raids on Chinese fishing boats in the past five years, she said, urging Seoul to strengthen its coastguard and let them use weapons more aggressively.

"The government should safeguard our maritime sovereignty by strengthening punishment of illegal fishermen and violent offenders," said the resolution.

China's foreign ministry Tuesday expressed "regret" at the officer's death.

Hundreds of coastguard officers and tearful family members attended the victim's funeral in the western port of Incheon Wednesday.

"We will come up with fundamental measures so that a tragedy like this will never take place again," President Lee Myung-Bak said in a speech delivered by an aide. The officer's three children sobbed as they held a photo of him.

The ashes of the 41-year-old will be buried in the national cemetery.

Officials say the Chinese captain accused of stabbing him will face a murder charge in the South while eight crew members are accused of obstruction.

Amid growing diplomatic strains, South Korea's embassy in Beijing was hit by an apparent airgun shot, prompting Chinese police to launch an investigation, according to Seoul's foreign ministry and media reports. No one was hurt.

A window was broken Tuesday apparently by a metal ball found nearby, a ministry spokesman said. Yonhap news agency said it appeared to have been fired from an airgun.