TAIPEI - Taipei health authority said Saturday that 21 tourists from a mainland tour group fell sick and were hospitalized following a meal in a Taipei restaurant.

The 40-people group from Ningbo, east China's Zhejiang Province, started the Taiwan tour on Feb. 26. They had lunch in the restaurant on Thursday and 21 of them suffered from vomiting, diarrhea and headache Thursday evening. On Friday morning they were sent to a local hospital.

"They were diagnosed with acute gastroenteritis," the hospital said, adding that only an 88-year-old had relatively serious symptoms and accepted transfusion. All members of the tour group returned to the mainland Friday afternoon.

Taipei health authority said in a statement that they had collected samples of food, utensils and restaurant environment for analysis. A hygienic check unveiled many problems, including scattering food materials, cockroaches, dirty fans and floors and a moldy ceiling.

The authority ordered a shutdown of the restaurant for three days and a thorough overhaul to rectify the problems. The owner may face a fine between 60,000 and 200 million new Taiwan dollars if failing to correct.

The mainland is the largest source of tourists for Taiwan. Last year, tourists from the mainland accounted for 40 percent in Taiwan's total.