Hundreds of riot police who clashed with some protesters from various political groups stopped the mob from getting into the hotel for more than seven hours, before dispersing it early on Thursday.

Local media reported several injuries to police and protesters.

It was unclear when Chen eventually left, but a staff member at another hotel where he was staying said he had returned around 2:30am.

Chen was due to meet Ma on Thursday afternoon in an unprecedented meeting that has sparked widespread anger across the self-governed island.

Name poser

There has been speculation about whether Chen will address Ma by his formal title of "president", given Beijing's regard of the island as a renegade province to be reunited with the mainland, by force if necessary.

"If he [Ma] cannot even defend his own title, what can he defend for us?"

Tsai Ing-wen, DPP leader

Tsai Ing-wen, chairwoman of the opposition Democratic Progressive Party, said the issue involved more than manners and political semantics.

"People feel anxious especially when we have to wonder whether the president, Taiwan's democratically elected president, will be addressed as president," she said.

"If he [Ma] cannot even defend his own title, what can he defend for us?"

Chen has drawn daily protests since he arrived on Monday for a five-day trip which included signing a trade deal many feel will ease tensions across the Taiwan Strait.

Earlier this week Chen and his Taiwanese counterpart, Chiang Pin-kung, signed a landmark agreement that expands aviation and shipping links between the two sides.

He also signed a deal to exchange rare animals with Taiwan, with Beijing offering two pandas in exchange for a Formosa serow and a Formosa sika deer offered by Hau Long-bin, Taipei's mayor.

And analysts say the meeting between Ma and Chen would be a positive development.

"The fact that Chen is seeing President Ma in Taipei has its political implications and it's a positive development in cross-strait ties," said George Tsai, a Taiwanese political observer from the Chinese Cultural University.

"It shows that Beijing does not deny the existence of the self-ruled island and acknowledges its jurisdiction."