Washington, Dec 3 (PTI) US Secretary of State Hillary Clinton has spoken with 12 world leaders, including the Presidents of Afghanistan and Pakistan, in the past one week to express her regret over the embarrassing release of secret diplomatic cables by WikiLeaks.

Yesterday, Clinton spoke to Pakistan President Asif Ali Zardari and President Fernandez de Kirchner of Argentina.

"They did talk about the importance of our relationship in both cases. She did express regret to both presidents for the release of classified documents," State Department spokesman P J Crowley said.

"In both conversations, they continued to look forward, and in both cases, President Zardari and President Fernandez de Kirchner continued to express the importance and friendship that these countries have with the United States," Crowley said.

Clinton had termed the release of classified US documents by WikiLeaks as an attack not just on the US, but the international community.