(Adds details, updates prices) LONDON, Oct 4 (Reuters) - Borrowing costs across the euro area nudged up on Monday, as unease that rising inflation could prompt central banks to unwind massive monetary stimulus sooner rather than later weighed on sentiment among bond investors. Ten-year government bond yields from Germany, France and the Netherlands rose almost 20 basis points in September as signs that inflation could prove stickier than expected and a hawkish shift from the likes of the U.S. Federal Reserve and the Bank of England rattled bond markets. While bond yields have found stable ground, the backdrop remains bearish with oil prices hovering around $80 a barrel and European gas prices on Monday rising to new highs. OPEC and its allies said on Monday they would stick to an existing pact for a gradual increase in oil output, sending crude prices to three-year highs and adding to inflationary pressures that consuming nations fear will derail an economic recovery from the pandemic. The recent rise in euro zone inflation has a structural driver in supply disruptions and the European Central Bank has to watch out for any sign of wages increases, ECB vice-president Luis de Guindos said, meanwhile. “It feels like inflation concerns are a bigger worry right now and we see that in equities as well,” Rene Albrecht, a rates strategist at DZ Bank, said. “We can call it stagflation, where you have higher inflation and weaker growth and maybe the markets are playing that theme today.” Germany’s 10-year Bund yield was 0.7 basis point (bp) higher by 1516 GMT on the day at -0.212%, within sight of almost three-month highs hit last week at around -0.17%. Italian bonds underperformed, with 10-year yields up around 1.6 bps at 0.836% - also near recent highs. Analysts said mayoral elections in Italy may be contributing an element of political uncertainty that helped explain the slight weakness in Italian bonds. The votes in Italy’s largest cities on Sunday and Monday are expected to show Matteo Salvini’s weakening grip of the right and see centre-left wins in the most high-profile contests. Exit polls on Monday showed Italy’s centre-left candidates were seen winning most of the big cities at stake in the local elections. Salvini, who seemed on an unstoppable rise when he led his League party to a triumph at European elections in 2019, has seen his popularity slide. “A poor performance may ... eventually push the League to leave the coalition, fragilizing Draghi’s government at the time several reforms (justice, university, tax, etc.) are due to be adopted,” analysts at Societe Generale said in a note. They were referring to former ECB chief Mario Draghi, who became Italian prime minister in February. Reporting by Dhara Ranasinghe Additional reporting by Danilo Masoni Editing by Andrew Heavens and Mark Potter Our Standards: The Thomson Reuters Trust Principles.