The city’s comptroller, William Thompson Jr., is using the muscle of the city’s pension fund to take on the Internet powerhouses Google and Yahoo.

Mr. Thompson, a likely 2009 mayoral candidate, has filed shareholder resolutions calling on the two search engines to create practices for dealing with censorship issues in communist countries like China, North Korea, and Cuba, as well as other “authoritarian” regimes including Iran, Syria, Burma, and Egypt.

The resolutions, which were filed last week, call on Google and Yahoo to resist demands for censorship and to ensure that they do not engage in any “proactive censorship.”

“Technology companies in the United States have failed to develop adequate standards by which they can conduct business with authoritarian governments while protecting human rights, including freedom of speech and freedom of expression,” Mr. Thompson said in a statement.

The search engines have both cooperated with foreign governments in different ways. They have each agreed to block Web sites on things like Falun Gong, Tiananmen Square, and Chinese free speech as a trade-off for getting access to lucrative, rapidly growing new markets of Internet users.

Their presence in China — which has constructed what has been called the Great Firewall of China — has become a delicate balancing act. On the one hand, it provides millions of people with information that they have never had. On the other hand, it blocks what the government doesn’t want them to see.

The city’s pension fund, which is now valued at about $96 billion, owns about $276 million worth of Google stock and about $110 million worth of Yahoo stock. The holdings represent well below 1% of the value of each of the California-based companies.

But, the pension fund does have clout. And, this is not the first time that Mr. Thompson, who won his re-election in a landslide in November, has used the fund to promote social ideals. In the past he has used it to pressure Halliburton, the global contracting company, to divest itself from business in Iran.

He has also leveraged the pension fund to get the supermarket chain Winn-Dixie to bar discrimination based on sexual orientation and to pressure the beverage giant Coca-Cola to allow an independent investigation into violent acts against union leaders at bottling plants in Colombia.

The most recent shareholder resolution says that if Google and Yahoo must legally comply with censorship demands to do business in a host country, they must inform their users of the arrangement and disclose to users if they are tracking their identities or sharing their information with a third party – like the home government.

The latter is something that Yahoo, which has been providing Internet services in China since 1999, has come under fire for. In 2004 the company provided the government with information about a journalist who was later arrested and put in prison by Chinese authorities.

It seems that at least in China, Google is already complying with many of Mr. Thompson’s demands, and that the resolution could have greater ramifications for Yahoo.

Those who follow Internet law had mixed reactions to Mr. Thompson’s move.

The executive director of the Berkman Center for Internet & Society at Harvard Law School, John Palfrey, applauded the resolution, but also said the two companies have stepped up efforts in the last year to comply with local laws in an ethical way.

“The spirit of the resolution in its general thrust is right on,” Mr. Palfrey said.

He said both companies are “seeking to do the right think in light of a very difficult situation,” but noted that shareholders generally have a right to keep checks on the companies they are invested in.

The director of the Center for Legal Policy at the Manhattan Institute, James Copland, had a different take on Mr. Thompson’s attempt use the heft of the fund to incite policy changes.

He said the rise of “shareholder activism and the so-called shareholder Democracy movement,” is damaging to American companies, distracting management from pursing profits.

“It’s from the right and it’s from the left,” Mr. Copland said. “You have people on the right trying to push shareholder resolutions relating to abortion and you have people on the left pushing things like environmental issues and these censorship issues. But they are all the same types of shareholder activism.”

The assistant comptroller for pension policy, Kenneth Sylvester, defended the move, saying that the office views it as a “business decision.” When companies rebuff human rights and cave on censorship issues they jeopardize their reputations and their financial bottom lines, he said.

He said the pension system has a “fiduciary” responsibility to protect its long-term investments and promote socially responsible behavior that is in compliance with the United Nations Declaration of Human Rights.

Mr. Sylvester said the pension funds plan to pursue other companies on this issue. He would not disclose which ones until the shareholder resolutions are filed. The fund does, however, own about $758 million worth of shares in Microsoft — another company that has taken heat for accepting censorship conditions from the Chinese government.

Mayor Bloomberg’s office declined to comment on Mr. Thompson’s resolutions. In the Winn Dixie case Mr. Bloomberg said he supported the goal of banning sexual discrimination, but did not think the pension fund should be used to advance social goals “no matter how admirable those goals are.”

A spokesman for Google, Jon Murchinson, said: “We, like our shareholders, place great importance on conducting business at home and abroad in an ethical and legal manner. We look forward to this resolution being considered by our shareholders at our next company meeting.”

In April, the New York Times quoted Google’s chief executive, Eric Schmidt saying: “I think it’s arrogant for us to walk into a country where we are just beginning operations and tell that country how to run itself.”

Yahoo representatives did not return calls yesterday.

The resolutions would go to the companies’ shareholders in proxies before annual meetings, unless a settlement is reached that resolves the issue or unless one of the companies chooses to mount a legal challenge to the resolution.