(Adds analysts, detail, updates currency) OSLO, June 8 (Reuters) - The outlook for Norwegian businesses brightened substantially in recent months amid a gradual lifting of COVID-19 restrictions, a central bank survey of business leaders showed on Tuesday, boosting the chances of one or more rate increases this year. “Contacts expect substantial output growth ahead as the measures ease through summer. Public building and infrastructure projects will amplify growth,” Norges Bank said of its socalled regional network survey. Norway’s crown currency strengthened on the news to trade at 10.0489 against the euro at 0810 GMT from 10.0730 ahead of the 0800 GMT data release. The sentiment index, most of which was collected from April 26 to May 11, is a key input to Norges Bank’s June 17 monetary policy meeting. “The network paints a rosy outlook of the economy. And with registered unemployment already dropping faster than expected by Norges Bank, the likelihood of a rate hike in September has increased,” Handelsbanken said in a note to clients. The central bank has said it aims to raise interest rates in the third or fourth quarter of 2021 but has also emphasised that the plan depends on clear signs that economic conditions are normalising from the pandemic. Danske Bank said a September rate increase was now all but guaranteed and that more may follow soon. “December suddenly becomes a live meeting for a potential 2nd hike this year,” Danske Bank economist Kristoffer Lomholt said on Twitter. As of Monday, Norway had fully or partly vaccinated 41.8% of adults against COVID-19, according to its Institute of Public Health. In total, 27.6% of those aged 18 or older had received two doses, while an additional 14.2% have had a single injection. (Reporting by Terje Solsvik, editing by Gwladys Fouche, Robert Birsel) Our Standards: The Thomson Reuters Trust Principles.