The world's most popular search engine has been dragged into what appears to be an escalating row between China and the United States on Internet controls.

Beijing yesterday stepped up accusations that Google is spreading obscene content over the Internet, a day after US officials urged Beijing to abandon plans for the installation of a controversial porn-filtering software, Green Dam, on new computers.

The Foreign Ministry yesterday accused Google's English-language search engine of spreading obscene images that violated the nation's laws, less than 24 hours after disruptions to the company's search engine and other services within China.

Spokesman Qin Gang did not directly say whether official action was behind the disruptions, but made plain the government's anger and said "punishment measures" taken against Google were lawful.

"Google's English language search engine has spread large amounts of vulgar content that is lewd and pornographic, seriously violating China's laws and regulations," he told a regular news conference.

The Internet Society of China last week ordered Google to block overseas websites with "pornographic and vulgar" content from being accessed through its Chinese-language version.

Late on Wednesday evening, Internet users in China were unable to access several Google services for up to two hours.

A spokesman for Google in China declined to comment.

Separately, US Commerce Secretary Gary Locke and US Trade Representative Ron Kirk on Wednesday voiced concerns over the "Green Dam" software in a letter to Chinese officials.

"China is putting companies in an untenable position by requiring them, with virtually no public notice, to pre-install software that appears to have broad-based censorship implications and network security issues," Locke said in a statement.

The government has said that Green Dam, which limits access to violent and pornographic websites, has to be included with all computers sold on the Chinese mainland starting July 1.

Questions:

1. What issue dragged Google into what appears to be an escalating row between China and the United States?

2. What is the name of the controversial porn-filtering software planned to be installed on all computers sold on the Chinese mainland?

3. According to the government from what date all computers sold on the Chinese mainland will have to include Green Dam?

Answers:

1. Internet controls.

2. Green Dam.

3. July 1.