UPDATE 2-British PM Truss tells allies to stand firm on Ukraine

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Truss warns of threats from Russia and assertiveness of China

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UK defence budget to rise to 100 bln pounds by 2030, minister says

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Truss aims to make U.S. relationship 'more special'

(Adds defence minister comments)

By Alistair Smout

LONDON, Sept 25 (Reuters) - British Prime Minister Liz Truss said allies should stand firm on Ukraine and ignore Russian President Vladimir Putin's "sabre-rattling".

Truss, who met U.S. President Joe Biden and France's Emmanuel Macron on her first foreign trip as prime minister to New York last week, in an interview with CNN called on like-minded democracies to be firm against "autocratic regimes".

Putin last week ordered a partial mobilisation of troops and raised the possibility of nuclear conflict. Truss said Putin was escalating his invasion of Ukraine because he wasn't winning and had made a strategic mistake.

"I think he didn't anticipate the strength of reaction from the free world," Truss said in the interview broadcast on Sunday.

"We should not be listening to his sabre-rattling and his bogus threats. Instead, what we need to do is continue to put sanctions on Russia and continue to support the Ukrainians."

Truss, who became prime minister earlier this month, has pledged to raise defence spending to 3% of Britain's GDP. Defence minister Ben Wallace told the Sunday Telegraph newspaper that that amounted to an annual defence budget of about 100 billion pounds ($108.56 billion) by 2030 - around double the current level.

Truss has taken a hard line against Russia and China, but has also been in dispute with some traditional allies, especially in Europe and the United States, over post-Brexit trading arrangements with the European Union.

She said she still wanted a negotiated solution on the so-called Northern Ireland protocol, that she and Biden agreed peace in the province needs to be preserved, and she still believed in the "special relationship" between Britain and the United States.

"I do think our relationship is special, and it's increasingly important at a time when we're facing threats from Russia, (and) increased assertiveness from China," Truss said.

"I'm determined that we make the special relationship even more special over the coming years."

Truss said she had a "very good meeting" with French President Macron in New York. She faced questions over Britain's relationship with France after she said during her campaign to become prime minister that "the jury's out" on whether Macron was friend or foe.

"I'm looking forward to working with him in the future," Truss said.

She said that Britain's allies needed to work together on their stance on China as well as Russia.

Asked if Britain would defend Taiwan militarily if China invades, Truss said: "We are determined to work with our allies to make sure that Taiwan is able to defend itself."

($1 = 0.9211 pounds) (Reporting by Alistair Smout; Editing by David Clarke, Toby Chopra and Susan Fenton)