Google on Monday decried restrictions on the Internet by China, Vietnam and other countries, calling them the "trade barriers of the 21st century" and making a case for new trade rules and talks.

"Trade officials and policymakers should be deeply concerned about the impact of Internet information restrictions on economic growth and trade interests," Google said in a policy paper.

"And, they should be ready to use current trade rules and negotiating forums to reduce this threat."

Google, which was involved in a spat with China this year over censorship and cyberattacks, said "more than 40 governments now engage in broad-scale restriction of online information, a tenfold increase from just a decade ago."

"The transformative economic benefits of the Internet are under threat, as increasing numbers of governments move to impose onerous limits on information flow," the Internet search and advertising giant said.

"Today more governments are incorporating surveillance tools into their Internet infrastructure; blocking online services in their entirety; imposing new, secretive regulations; and requiring onerous licensing regimes that often discriminate against foreign companies," it said.

"These actions unnecessarily restrict trade, and left unchecked, they will almost certainly get worse," Google warned.

Google said governments should honor World Trade Organization obligations "and develop new international rules that provide enhanced protection against these trade barriers of the 21st century."

"Governments in the United States, the EU and elsewhere have a variety of existing trade agreements -- principally the WTO General Agreement on Trade in Services (GATS) -- that can and should be applied where appropriate to combat restriction and disruption of information delivered by the Internet," it said.

Google compared government blocking of an Internet service "to a customs official stopping all goods from a particular company at the border."

"Censorship on the Internet poses a significant economic threat to companies seeking a level playing field as they establish markets overseas," Google said.

"When a foreign government blocks or technically interferes with a website, it has either barred or undercut that business' access to the market," it said.

"In China, for instance, numerous US Internet services have been kept out or severely restricted, while Chinese versions of the same services have been permitted to operate," Google said.

"Governments including China and Vietnam censor both services and content at international telecommunications network gateways, and subject Internet traffic coming from outside the country to special filtering regimes," Google said.

It cited China's periodic shutdowns of Facebook, Flickr, Twitter and Foursquare and said Vietnam has blocked Facebook since last year.