BEIJING, Sep. 4 (AP) -- North Korea has suspended travel by Chinese tourists due to damage from heavy summer flooding, but is still allowing business travelers into the isolated nation, travel agencies said Monday.

Sun Hong, manager of Dandong Tianma Travel Agency, said his office received notice from the North's tourist department on Aug. 8 saying that "all tourist trips ... would be suspended due to railway damage caused by flooding."

Business trips were not be affected, according to the notice, which did not say when tourists would be allowed back or give other details.

China's National Tourist Administration did not respond to telephone or faxed requests for information.

"The suspension has affected us a lot because the trips to North Korea is an important part of our business," Sun said by phone from Dandong, a Chinese city that borders North Korea and is the main crossing for trains bound for the North Korean capital, Pyongyang.

Most Chinese tourists going to North Korea take the train from Dandong. Flying is not a common choice as flights are more expensive and less regular than trains.

North Korean media reports have said that hundreds died in the July floods but have not given specific numbers.

South Korea's intelligence agency believes the toll of dead and missing is about 800-900. The extent of damage is not known because the secretive North tightly controls all information.

He said his company arranges four-day visits for an average of 100 Chinese tourists daily.

The manager of Dandong Railway International Travel Service, who would give only his surname, Zhang, said the "disastrous floods had affected traffic in parts of North Korea."

He said it was unlikely that travel would resume this year since the tourist season normally ends in October.

China is the North's last major ally and its key source of aid, oil and trade.

Tourists usually go on closely chaperoned trips to Pyongyang.

Relations have been strained since North Korea launched missiles in July and China joined in a U.N. Security Council resolution condemning the tests.

Beijing is trying to dissuade the North from a nuclear test amid media reports of suspicious activity at a possible underground nuclear test site.

Pyongyang claims it has nuclear weapons, but hasn't performed any known test.