TORONTO — Political leaders of the world’s 20 leading industrial and developing nations took note at their economic summit of the devastating oil spill in the Gulf of Mexico in their concluding statement yesterday.

The document recognized “the need to share best practices to protect the marine environment, prevent accidents, . . . and deal with their consequences.’’

The April 20 explosion on the BP -leased Deepwater Horizon rig unleashed the worst offshore oil spill in US history. BP is London-based and the disaster has contributed to strains between the United States and Britain.

Britain’s new conservative prime minister, David Cameron, told reporters BP was working hard to cap the well, “clean up the mess,’’ and compensate victims. At the same time, he said, “what we all want is for this important company to be strong and stable for the future.’’

Cameron and President Obama held a meeting yesterday on the sidelines of the economic summit.

Obama also said the international community must stand behind South Korea and send a clear signal to North Korea that its provocative behavior is unacceptable. North Korea is blamed for the deadly sinking of a South Korean warship.

Forty-six South Korean sailors were killed in the March attack.

“It is absolutely critical for the international community to rally behind’’ South Korean President Lee Myung-bak, Obama said.

“There’s a difference between restraint and willful blindness to consistent problems,’’ Obama said, referring to Beijing’s worry that instability in the North could cause major problems across the border in China.

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