US President Barack Obama has said North Korea must be "held to account" for the sinking of a South Korean warship¹.

美国总统奥巴马称，朝鲜必须为朝鲜战舰沉没事件“负责任”。

President Obama: "There has to be consequences"

He said he stood with South Korean leader Lee Myung-Bak, and condemned² Pyongyang's "irresponsible behaviour".

His comments came shortly after the G8 group of industrialised nations meeting in Toronto condemned the sinking of the corvette（轻巡洋舰） Cheonan earlier this year.

North Korea has denied attacking the ship.

An international investigation⁴ concluded that it was sunk by a North Korean torpedo⁵.

After meeting the South Korean leader on the sidelines of the summit, Mr Obama said: "There has to be consequences for such irresponsible behaviour."

The G8 leaders also criticised of North Korea - and Iran - over their nuclear activities, and they described the Israeli blockade（封锁） of the Gaza Strip as "not sustainable".

And they admitted that the global financial crisis had compromised efforts to meet UN targets for reducing world poverty.

Canada is also hosting a summit of the wider G20 group of industrial and developing powers, which will will discuss the global economy and financial reform.

Thousands of demonstrators marched on the G20 summit on Saturday in what is being reported to have been a largely peacefully rally that saw outbreaks of violence on its edges. These saw groups of young men scuffle（混战，扭打） with riot police（防暴警察） and set fire to at least two patrol cars.

Security concerns

In their final summit statement, the G8 - the US, Canada, Germany, UK, France, Italy, Russia and Japan - said: "We deplore⁶ the attack on 26 March that caused the sinking of the Republic of Korea's naval⁷ vessel⁸, the Cheonan, resulting in tragic⁹ loss of 46 lives."

Noting that an international investigation had found that, despite its denials, Pyongyang was to blame for the attack that sank the warship, the statement adds: "We condemn³, in this context（关于这点，由此而论） , the attack which led to the sinking of the Cheonan.

"We demand that the Democratic People's Republic of Korea refrain from（克制，抑制） committing any attacks or threatening hostilities¹⁰ against the Republic of Korea."

Reuters news agency says the statement was not as strongly worded as some nations, including the United States, had hoped. It says Russia was said to have held out against stronger language.

The statement also expresses the G8 leaders' "gravest concern that the nuclear test and missile activities carried out by the Democratic Peoples' Republic of Korea have further generated increased tension in the region and beyond, and that there continues to exist a clear threat to international peace and security."

The document calls on Iran to carry out a "transparent¹¹ dialogue" over its controversial nuclear programme.

"We are profoundly concerned by Iran's continued lack of transparency regarding its nuclear activities and its stated intention to continue and expand enriching uranium," it says.

The UN Security Council earlier this month approved a fourth round of sanctions against Tehran for failing to halt nuclear enrichment. The measures include tighter finance curbs¹² and an expanded arms embargo¹³（武器禁运） , but not the crippling（造成严重后果的） sanctions the US had wanted.

On Gaza, the communique says the G8 leaders "deeply regret" the loss of life and injuries in the aid flotilla（小舰队） that was stormed by Israeli commandos last month as it was approaching the Palestinian territory. Nine Turkish activists¹⁴ died on board the flotilla's main ship.

In a reference to the Israeli blockade of the Palestinian territory, which is controlled by Islamist group Hamas, it says: "We urge all parties to work together... to ensure the flow of humanitarian¹⁵ and commercial goods and persons, to and from Gaza. The current arrangements are not sustainable and must be changed."