TOLUCA - US President Barack Obama said on Wednesday his government needed to follow its established process to decide whether to allow the Keystone XL crude oil pipeline from Canada to go ahead, stressing that concerns about climate change needed to be at the forefront of government decisions.

"I said previously that how Keystone impacted greenhouse gas emissions would affect our decision, but frankly it has to affect all of our decisions at this stage," Obama told a news conference concluding a North American summit.