BEIJING - China told Taiwan Wednesday not to jeopardise cross-strait relations after a report that Washington expects to agree the sale of two warships to the island.
Beijing said it "firmly opposed" all foreign arms sales to its neighbour, which it regards as part of its territory awaiting reunification - by force if necessary.
Taipei said the planned arms sales covered "defensive weapons" and would not threaten the mainland.
The White House is set to authorise the sale of two guided-missile frigates to Taiwan as early as this week, Reuters said, citing US congressional sources.
In a joint statement, the Chinese Communist Party's Taiwan Affairs Office and the State Council, or cabinet, said Beijing "firmly opposes sales of weapons, military hardware or technology to Taiwan by any country in any form or under any pretext".
"We hope Taiwan cherishes the hard-earned good situation for the peaceful development of bilateral relations and do more to help improve and develop ties between the two sides," the statement added.
Taiwan's defence ministry spokesman David Lo said Beijing had nothing to worry about.
"We've noticed the reactions from mainland authorities regarding the planned arms sales," he said.
"It was unnecessary as they are all defensive weapons which are aimed for increasing our self-defence capabilities and helping maintain peace in the Taiwan Strait and won't threaten the mainland."
Lo added: "Nor have we the intention of engaging in an arms race with the mainland."
Lo declined to confirm the arms sales but said the Taiwanese military has "presented shopping lists" to the US, including two Perry-class frigates, "which have been discussed by the US Congress".
China's foreign ministry warned the US on Tuesday that arms sales to Taiwan would damage Sino-US relations.
"China strongly urges the US side to seriously realise the high sensitivity and severe harmfulness of arms sales to Taiwan, live up to its commitments and stop arms sales to Taiwan," said foreign ministry spokesman Hong Lei at a briefing.
Relations between Beijing and Taipei have warmed under current Taiwanese president Ma Ying-jeou of the Kuomintang party. But China still sees Taiwan as a breakaway territory and refuses to renounce the use of force should it declare formal independence.
China and Taiwan split at the end of a civil war in 1949.
The United States recognises China rather than Taiwan, but remains a main ally and leading arms supplier to the island, providing a source of continued tension with Beijing.
Taiwan will elect a new president in January, with the candidate of the pro-independence opposition Democratic Progressive Party, Tsai Ing-wen, tipped to win.
She has pledged to maintain the status quo if she wins but some analysts have questioned whether cross-strait peace could be maintained.