(Adds details on Jan-June figures) BRASILIA, Aug 3 (Reuters) - Industrial production in Brazil was unchanged in June from the previous month, figures showed on Tuesday, meaning the sector expanded 12.9% in the first half of the year to stand slightly bigger than it was just before the COVID-19 pandemic. Statistics agency IBGE said, however, that output in June fell in three of the four main economic categories and in 14 of the 26 sectors surveyed, suggesting the underlying figures were weaker than the stability shown in the headline number. The no change on the month was exactly as predicted in a Reuters poll of economists, while the 12.0% increase from June last year was slightly higher than the 11.8% growth forecast in the poll. IBGE survey manager Andre Macedo said the effects of the second wave of the pandemic this year are still being felt across the sector. “In the industrial sector there are several challenges caused by restriction measures, such as lower production, the difficulty in obtaining raw materials and rising production costs,” Macedo said, adding that high unemployment is also affecting demand. IBGE said 14 of the 26 sectors surveyed saw a fall in output in June, the biggest drag being a 3.8% fall in auto vehicles and parts production. Only one of the four major categories - capital goods - saw output rise in June, IBGE said. Compared to June last year, overall production rose 12.0% due to base effects. IBGE figures show, however, that the industrial sector is still 16.7% smaller than its peak in May 2011. (Reporting by Jamie McGeever, Editing by William Maclean) Our Standards: The Thomson Reuters Trust Principles.