How a man from mainland China managed to cross the Taiwan Strait in a small rubber boat is a mystery authorities in Taipei are trying to unravel on Tuesday.

Crossing the highly-militarized waters undetected would be no simple task and if there was any security "shortcomings" that needed to be addressed, the Taiwanese want to know them.

The 33-year-old man, only identified as Zhou, reportedly traversed the 100-mile stretch of water without being detected by a single patrol. The Taiwan Strait is considered to be one of the world's most heavily-policed waterways with both Chinese and Taiwanese vessels patrolling the area.

Authorities said they are looking to confirm the man's story. Zhou told authorities that he had traveled from Quanzhou in China's Fujian province. Zhou was spotted traveling in his small rubber dinghy by authorities near the port of Taichung. He reported traveled to Taiwan in search of "freedom and democracy."

Taiwan's defense minister Chiu Kuo-cheng said he has instructed officials to investigate how the man was able to travel to the country without being detected.

"We will get in touch with the Coastguard, we will notify each other when there is a situation, to find out the reasons and make improvements," Chiu said.

According to local reports, Zhou had bought his 2.6 meter by 1.5 meter rubber boat from the internet. He reportedly fitted it with an outboard motor. He traveled to Taiwan carrying nothing but 90 liters of fuel.

Police said Zhou was seeking political sanctuary in the country. He is reportedly being held in a detention center where he will undergo a 14-day quarantine.

Taiwan's navy chief of staff, Chiang Cheng-Kuo, said Zhou was not carrying enough fuel to have made the journey. Chiang said he doubts Zhou's story. However, if his story is true, the size of his vessel made it impossible to detect using land-based or vessel-mounted radar, Chiang said.

"There are no blind spots, but we do not discount the possibility that [Zhou] was hidden by the cargo ships and other larger vessels," the director of the Fourth Patrol District Command of Taiwan's Coast Guard, Hong Yishun, said in an interview.