Net freedom could suffer after the US steps back from its role as ultimate overseer of the global network, former US President Bill Clinton has said.
Many of the governments keen to help oversee the net just wanted to use it to silence dissent, he said.
Mr Clinton made his comments during a debate sponsored by his charitable foundation, Clinton Global Initiative.
The US had been a good steward of the net and had helped keep it open and accessible, he said.
Mr Clinton said it was clear ongoing revelations about National Security Agency surveillance had fuelled demands for the US to step back from its historical role as net overseer.
But, he added, it was a "tribute" to the US that it had for a long time kept the net "free and open" and a place where people could openly criticise lawmakers and heads of state.
"The internet has flourished in freedom," said Mr Clinton.
"A lot of people who have been trying to take this authority away from the United States want to do it for the sole purpose of cracking down on internet freedom and limiting it and having governments protecting their backsides instead of empowering their people," he said.
In mid-March the US government announced its intention to hand over its power to oversee net policy to an international multi-stakeholder group.
The actions and decisions of that group would be co-ordinated by Icann - the body set up by the US in 1998 to administer the net's addressing system.
"I understand in theory why we would like to have a multi-stakeholder process. I favour that," Mr Clinton said.
"I just know that a lot of these so-called multi-stakeholders are really governments that want to gag people and restrict access to the internet. "
Support for Mr Clinton's fears was given by Wikimedia Foundation boss Jimmy Wales, who shared the platform with the former president.
He also said he was "worried" about net freedom when the US was no longer in charge.
Mr Wales said he was an active member of Icann and regularly attended discussions on how to make the net more sensitive to "local culture".
But, he said, sensitivity was often just another word for censorship and ending American involvement might make it much harder to defeat calls for the net to be more locally malleable.