UK long-term borrowing costs have jumped to their highest level since 1998, amid concerns over rising inflation and political uncertainty ahead of this week’s local elections. The yield on 30-year UK government bonds – also known as gilts – reached a 28-year high on Tuesday afternoon, up 0.14 percentage points to 5.798%. Gilt yields move counter to the value of the bonds, meaning their prices fall when yields rise. Rising yields on these bonds mean it costs more for governments to borrow from financial markets. The yield on 10-year gilts also rose, lifting by 0.15 percentage points to 5.122%, but remains below recent highs reported last month. The yield on US 10-year treasury notes was flat on Tuesday but has steadily risen in recent weeks. Gilt yields have grown amid growing predictions that the conflict in Iran will drive higher inflation due to spiking energy costs, which is then likely to cause the Bank of England to increase interest rates.…