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LONDON, April 11 (Reuters) - British 20- and 30-year government bond yields were on course on Friday for their biggest weekly jump since the aftermath of Liz Truss's "mini-budget" in 2022 as the United States and China escalated a trade war, igniting long-term inflation worries.

Thirty-year gilt yields GB30YT=RR were up by around 7 basis points at 5.497% at 1640 GMT, tracking a bigger rise for U.S. Treasury bonds and taking their increase since the start of the week to almost 40 basis points.

That vertiginous climb included a sharp fall of around 17 basis points on Thursday when U.S. President Donald Trump suspended the bulk of his latest tariffs on trade partners but increased them for China which responded in kind.

Twenty-year gilt yields were up by a similar amount over the week, also the biggest increase since Truss's short-lived time as UK prime minister.

U.S. 30-year bond yields US30YT=RR were heading for their largest weekly increase since 1982.

"The acute volatility is akin to that seen at only the most extreme of circumstances," Barclays fixed income strategist Moyeen Islam said about the week's market moves.

The snowballing of tariff announcements has caused investors to rethink the outlook for the world economy, including the risk of higher long-term inflation.

"Hence, despite the U.S. tariff strategy being interpreted by the market as a near-term growth negative impulse for the UK (and deflationary), leading to a pricing-in of rate cuts, long-end gilts have failed to perform, and have actually cheapened instead," Megum Muhic, vice president rates strategist at RBC Capital Markets, said.

Yields on two-year British gilts - which are sensitive to short-term speculation about official interest rates - have risen this week by a lot less than longer-duration British government bonds.

However, they were up by 12 basis points for the day at 4.028% shortly before Friday's close.

Stronger-than-expected growth data for the UK economy, released earlier on Friday, prompted investors to lower slightly their bets on Bank of England interest rate cuts this year.

Investors on Friday were pricing in 75 bps of further BoE rate cuts between now and the end of December, down from more than 90 bps on Thursday but still above the roughly 50 bps expected before Trump's tariff announcements last week.

((peter.graff@thomsonreuters.com;))