Taipei  - The United States, in a move that is seen as an upgrading of its ties with Taiwan and one which might annoy China, plans to post Marines at its unofficial embassy in Taipei.

A US State Department advertisement which appeared in the Taipei Times daily on Saturday called for bids from contractors to build a new office compound for the American Institute in Taiwan (AIT), the de facto US embassy since Washington cut diplomatic ties with Taiwan to recognize China in 1979.

The contract worth 45-60 million dollars also includes building Marine Guard Quarters on the compound.

The new AIT compound, occupying 65,468 square metres in the Neihu suburb of Taipei, will replace the current AIT compound in downtown Taipei, which accommodates some 200 US and local staff and is protected by Taiwan police.

Analysts said that as the US posts Marines at its embassies and consulates, Washington's sending Marines to the AIT in Taipei would constitute an upgrading of the status of the institute, which Beijing certainly does not like to see.

When the US switched recognition from Taipei to Beijing in 1979, its signed the Taiwan Relations Act, pledging to preserve cultural, trade and military ties with Taiwan. The US remains Taiwan's top arms supplier and one of Taiwan's top trading partners.

Over the years the AIT has served as the unofficial US embassy in Taiwan - issuing visas to Taiwan citizens, holding trade talks and passing Washington's messages to Taipei and vice verse.

In 2005, the US began placing military attaches at the AIT, though they did not wear uniforms.

China, which sees Taiwan as its breakaway province, has demanded the US stop selling Taiwan weapons and to keep its ties with Taipei unofficial, in line with the "one China" principle which Beijing has asked all foreign countries to observe.

Only 23 mostly-small nations recognize Taiwan, but dozens of countries - including the US, Britain, France, Russia, Japan and South Korea - have opened representative offices in Taipei despite having diplomatic ties with Beijing. (dpa)