Google will continue to consider co-operation with long-term rival Yahoo, according to chief executive Eric Schmidt.

Last month Yahoo began a two-week trial of running adverts provided by the Mountain View firm. The test-run took place during a pivotal stage in Microsoft's attempt to purchase the search giant, a bid that collapsed earlier this week.

And while the advert trial has now finished, Google has indicated that it may pursue further collaborations with Yahoo.

"We view the test as successful," said Schmidt, speaking just before Google's annual shareholder meeting. "That's a good basis to talk to Yahoo some more."

Schmidt also said that any future partnership would be structured to meet anti-trust concerns.

Google also announced that generating new revenues from YouTube would be a key part of its strategy for the year ahead. But the video sharing site, and the recently-purchased DoubleClick advertising firm, will take time to become profitable, said Google co-founder Sergey Brin.

"They both have potential, but for it to be a sizable part of our revenue, you're going to have to wait at least a couple of years," he said.