A petition website that demands an investigation into the US biological laboratory at Fort Detrick, Maryland, was subject to two cyberattacks from US-based hackers on Saturday, a move its operator said exposed the fear from certain forces in the United States after seeing growing support for an inquiry.

In an online statement, the Global Times newspaper, which launched the petition, said it strongly condemned the cyberattack, and that it is the right of Chinese internet users to conduct a petition.

Its servers have withstood the attack, it said, and only minor damage was caused, even though more attacks could occur.

"We will be fully prepared and try to withstand the attacks to protect the petition and the right of expression of Chinese internet users," it said.

By Sunday, more than 11.4 million people had signed the petition, which urges the World Health Organization to conduct a thorough investigation into the Fort Detrick laboratory, which was shut down by the US Centers for Disease Control and Prevention amid safety concerns over its research involving dangerous microbes like the Ebola virus in July 2019.

The newspaper said it expects more people to sign the petition, including people from other countries, with news of the petition continuing to spread.

Zhao Lijian, a Chinese Foreign Ministry spokesman, said Chinese people had delivered a clear message in signing the petition for the investigation.

He told a news briefing on Wednesday that the increasing endorsement reflects Chinese people's aspirations and their anger over political manipulation by some in the US.

He cited events including a "respiratory outbreak" of unknown cause in which more than 60 residents at a retirement community in northern Virginia fell ill in the month that the Fort Detrick laboratory was closed. Later in 2019, Maryland, where Fort Detrick is based, witnessed a doubling of the number of residents who developed a respiratory illness related to vaping, Zhao said.

"A probe into Fort Detrick is long overdue, but the US has not done it yet," Zhao said. "Investigating Fort Detrick is an appeal of people all over the world, including the Chinese people. It is a question that the US must answer."