TAIPEI, June 1 (Reuters) - Taiwan and the United States will sign the first deal under a new trade talks framework on Thursday, both governments said, boosting ties between the two at a time of heightened tensions with China over the democratically-governed island.

Taiwan and the United States started talks under what is called the U.S.-Taiwan Initiative on 21st Century Trade last August, after Washington excluded Taiwan from its larger pan-Asian trade initiative, the Indo-Pacific Economic Framework.

Taiwan's Office of Trade Negotiations said in a brief statement the first agreement under the framework would be signed in Washington on Thursday morning U.S. time, but gave no other details.

The U.S. Trade Representative's office said Deputy United States Trade Representative Sarah Bianchi would attend the event, but also did not elaborate.

Last month, the two sides reached agreement on the first part of their trade initiative, covering customs and border procedures, regulatory practices, and small business.

After the initial agreement is signed, negotiations will start on other, more complicated trade areas including agriculture, digital trade, labour and environmental standards, state-owned enterprises, and non-market policies and practices, the USTR has previously said.

The pact is not expected to alter goods tariffs, but proponents say it will strengthen economic bonds between the United States and Taiwan, open the island to more U.S. exports, and increase Taiwan's ability to resist economic coercion from China.

Beijing has denounced the trade talks as it does with all forms of high level engagement between Taiwan, which it claims as its own territory, and the United States.

Taiwan strongly rejects China's sovereignty claims, which Beijing has been trying to push on Taipei through repeated military activities including war games around the island.