Taiwan's pro-reunification Labor Party on Thursday condemned the island's Democratic Progressive Party authorities for allowing a proposed expansion of the American Institute in Taiwan's office compound in Taipei.

The AIT is reportedly planning to expand its facilities, including taking over nearby school land, for additional office and warehouse space, a move the institute said was meant to reinforce the US' "rock-solid commitment to Taiwan".

If the expansion goes ahead, the AIT's new premises will exceed the size of the United Nations Headquarters and surpass the area occupied by the US Embassy in China, according to the Labor Party.

It strongly criticized the expansion plan in a statement, questioning why the AIT insists on expansion when the existing facilities already exceed the actual needs of its 600-strong staff.

It also raised concerns that the AIT might be planning to add helicopter pads and station more US troops to evacuate US citizens and DPP military and government officials in the event of a conflict to avoid a repeat of the scramble to evacuate the US Embassy in the city then known as Saigon at the end of the Vietnam War.

The party denounced disparities in land use in Taiwan, comparing the low rent for AIT premises with the struggle Taiwan's youth face in finding affordable housing and DPP government claims that there is a lack of public land for additional social housing.

It added that the fact that the AIT is seeking to expand onto school land is an encroachment on the island's education resources, and questioned why the DPP's high-ranking officials are allowing the expansion to happen.

The party called for unity among the Taiwan people, firm support for their demands and resistance from residents.