European banks and companies may be interested in participating in China's major globe-spanning investment initiative — but first, they need to actually learn more about its details, according to a top European Union official.

Speaking with CNBC on Thursday from Beijing, European Commission Vice President Maros Sefcovic said his conversations with major companies indicated that China needed to be more transparent if it wants to win European corporate buy-in for its "Belt and Road." That initiative, a cornerstone of Chinese President Xi Jinping's foreign policy, seeks to create a massive web of shipping, rail, road, and digital networks that establishes Beijing as a linchpin for the world.

China is reportedly seeking more outside involvement in its bid to invest in and support that infrastructure development, and Sefcovic is part of a lengthy list of global officials attending this week's Belt and Road Forum.

European companies, he told CNBC, are first and foremost looking for information.

"They would love to be more involved in the Belt and Road Initiative, but we need a little bit more information coming for our companies: how they can participate, how they can bid in the public procurement — and of course also the sustainable financing of this project is important because it's raised some concerns also in Europe," he said.

The worries about the financing approaches of the initiative come in the wake of several countries canceling or seeking to renegotiate their Belt and Road projects because of concerns about establishing onerous debt to Chinese sources. Notably, Sri Lanka relinquished a strategic port to Beijing in 2017 after it couldn't pay off its debt to Chinese companies.