Chinese state media have accused Taiwanese President Tsai Ing-wen of using 'dirty tactics' for her election win

China on Sunday slammed officials from the US and other countries for congratulating Taiwan President Tsai Ing-wen after she was re-elected with a landslide victory in a stunning rebuke of Beijing's campaign to isolate the self-ruled island.

Tsai, who had pitched herself as a defender of liberal democratic values against an increasingly authoritarian China, secured a record-breaking win in Saturday's presidential election.

US Secretary of State Mike Pompeo, as well as top diplomats from Britain and Japan, issued statements congratulating Tsai and the island's democratic elections.

But Beijing, which views Taiwan as part of its territory, denounced their actions as violating the one-China principle.

"The Chinese side expresses strong dissatisfaction and resolute opposition to this," said foreign ministry spokesman Geng Shuang.

"We oppose any form of official exchange between Taiwan and countries that have established diplomatic relations with China," he said in a statement.

Chinese state media also sought to downplay Tsai's victory and cast doubt on the legitimacy of her campaign by accusing the Taiwanese leader of "dirty tactics" and cheating.

Tsai and her Democratic Progressive Party (DPP) used "dirty tactics such as cheating, repression and intimidation to get votes, fully exposing their selfish, greedy and evil nature", said official news agency Xinhua in an op-ed Sunday.

Xinhua also accused Tsai of buying votes, and said "external dark forces" were partly responsible for the election results.

Beijing, which has vowed to one day take Taiwan -- by force if necessary -- loathes Tsai because she refuses to acknowledge the idea that Taiwan is part of "one China".

China doubled down on its "one-China principle" after Tsai's victory, with Geng emphasising Sunday that "regardless of what happens in Taiwan, the basic facts won't change: there is only one China in the world and Taiwan is part of China".

"The Chinese government's position won't change," he added in a statement.

-'Orchestrating tensions'-

Over the last four years, Beijing has ramped up economic, military and diplomatic pressure on the island, hoping it would scare voters into supporting Tsai's opposition.

But the strong-arm tactics have backfired and voters flocked to Tsai's DPP, fuelled in part by China's hardline response to months of huge and violent pro-democracy protests in Hong Kong.

Chinese state media have accused Tsai, who frequently invokes Hong Kong's protests as a warning about a Beijing-controlled Taiwan, of fear-mongering.

Tsai and her party are "orchestrating tensions", wrote the nationalistic Global Times on Saturday.

At the end of 2019, the Taiwanese leader "wantonly hyped up the so-called threat from the Chinese mainland while slandering Han Kuo-yu's mainland connections", it said, referring to her Beijing-friendly main opponent from the Kuomintang party.

Chinese state media also dismissed Saturday's election results as an anomaly in long-term ties between Taiwan and the mainland, with Xinhua describing Tsai's win as a "fluke".

"The fact that the Chinese mainland is getting increasingly stronger and the Taiwan island is getting weaker is an inevitable reality," added the Global Times.

"Recognising and complying with the reality is the only feasible option for Taiwan's peaceful development."