Internet giant Google will remove all books still on sale in Europe from a US online market offering millions of titles that are out of print in the United States, the company said on Monday.

Concessions to European publishers come amid controversial plans that opponents say represent a "big landgrab" of the world's stock of up to nine million out-of-print and out-of-copyright books.

Google, which counts some three million titles potentially in play outside the US, must instead negotiate agreements with European publishers and authors.

"Books that are commercially available in Europe will be treated as commercially available under the settlement," Google said in a statement.

"Such books can only be displayed to US users if expressly authorised by rights holders," it added, as hearings got under way in Brussels on Monday to determine the European Union's response to the US deal.

The company also promised to bring a European publisher and a European author onto its board.

Previously, rights holders were considered to have "opted in by doing nothing," according to British trade magazine The Bookseller's managing editor, Philip Jones.

Google has digitised millions of books already, which Jones says "people have described as a big landgrab." He stressed: "Publishers (still) want to see more clarity."

Angela Mills Wade, executive director of the European Publishers Council, said the definition of "commercially available" remained a problem area for some members.

She said: "If a copy of an English-language book published in Europe finds its way to a US library, Google could scan it even if the rights haven't been sold in the US market, possibly harming the publisher's own opportunities to sell those rights."

Germany said last week it opposed the US legal settlement citing similar grounds, although the EU itself wants to dust down out-of-print and so-called 'orphaned' books for future generations.