“Everything is back to normal,” said a National Immigration Agency (NIA) spokesman immediately after the computer system resumed full operation at 5:10 p.m.

He said the breakdown started at 5 a.m. on Tuesday when two backup systems collapsed one after the other, forcing immigration officers at airports and on the offshore islands to manually clear passengers' exit and entry.

Most seriously affected was Taoyuan International Airport, where more than 20,000 passengers, many of them foreign nationals, queued in long lines before the immigration counters throughout Tuesday.

All 40 counters at Taoyuan's two terminals were open yesterday morning to clear 5,000 jittery passengers.

Also affected were Kaohsiung International Airport at --iaogang, Songshan Airport in Taipei, Taichung Airport, and two harbor checking points on Quemoy and Matsu.

Chinese visitors can come to Taiwan and go back to China via Kinmen and Matsu. They have to be cleared by immigration officers.

Mitac International, contractors for the computer systems for immigration, completed repairs later than had been scheduled.

Hsieh Lih-kung, director-general of the NIA, promised Tuesday the systems would be fully accessible by 12 noon.

Repairs were completed five hours late.

Initial investigations ruled out human errors as the cause of the breakdown, which made Taoyuan International look like a second-rate airport in a developing country.

Asked if some wanted criminals got out of country during the computer shutdown, Hsieh said an investigation would get under way.