TAIPEI (REUTERS) - A group of six US lawmakers, including chairman of the US Senate Foreign Relations Committee Bob Menendez, landed in Taiwan on Thursday (April 14) for a previously unannounced visit, in a show of support to the island in the face of Chinese pressure.

The United States has no formal relations with Chinese-claimed Taiwan, but is its most important international backer and arms supplier.

Taiwan has been heartened by the continued US support offered by the Biden administration, which has repeatedly talked of its "rock-solid" commitment to the democratically governed island. That has strained already-poor Sino-US relations.

The bipartisan group, which will meet Taiwan President Tsai Ing-wen on Friday morning on their two-day visit, arrived at Taipei's downtown Songshan airport on a US Air Force aircraft and was greeted by Taiwan Foreign Minister Joseph Wu.

The visit shows not only the bipartisan US support for Taiwan, but also the "rock solid" nature of Taiwan-US relations, Presidential Office spokesman Xavier Chang said in a statement.

"The Presidential Office looks forward to continuing to deepen the Taiwan-US partnership through this face-to-face exchange, and continuing to work together to contribute to global and regional peace, stability, prosperity and development," he added.

Mr Menendez, a Democrat, is a staunch supporter of Taiwan. In February he co-proposed a Bill that would require the US to negotiate the renaming of Taiwan's de facto embassy in Washington as the "Taiwan Representative Office".

Senior Republican Senator Lindsey Graham is also on the trip.