NEW YORK | China forced the last remaining foreign journalists out of Tibet today, and stepped up restrictions on Internet and radio reports from people within the country, a media watchdog said.

Georg Blume, a correspondent for German newspapers Die Zeit and taz, and Kristin Kupfer of the German EPD news agency, left today after being confronted by an official who threatened to cancel their Chinese visas, Reporters Without Borders said.

Earlier this week, Economist correspondent James Miles and a group of 15 Hong Kong reporters also were forced out.

“If they don’t have anything to hide, then why are they making foreign journalists leave? It’s clear that they don’t want any witnesses,” said Vincent Brossel, who heads Reporters Without Borders’ Asia desk.

Beijing has warned foreign tourists and journalists to stay away from a huge expanse of territory across four provinces, acknowledging that last week’s anti-government protests have spread far beyond Tibet’s borders.

The protests, led by Buddhist monks, started peacefully but erupted into rioting on Friday, drawing a harsh response from Chinese authorities. The Chinese crackdown has drawn worldwide attention on the country’s human rights record, threatening to overshadow Beijing’s attempts to project an image of unity and prosperity in the lead-up to the Olympic Games in August.

The German left-leaning daily taz posted a story on its Web site protesting Blume’s expulsion.

“Apparently the Chinese government cannot tolerate any further Western witnesses in Tibet. That is, for us, no real surprise — the position of the People’s Republic on press freedom is well known,” wrote Reiner Metzger, the newspaper’s deputy editor.

Reporters Without Borders said Chinese authorities are using “jamming stations” to block radio broadcasts out of Tibet and have asked Internet cafe owners to increase the surveillance of their clients.

The group also obtained a message it said was being sent to Tibetans living outside of Tibet from the “Internet Surveillance Bureau,” which said: “It is forbidden to post news about Tibetan events ... anyone infringing on this ban will have their IP address sent to the police who will take the necessary steps.”