By Niclas Mika AMSTERDAM, Nov 18 (Reuters) - Just days before a general election, Dutch Defence Minister Henk Kamp was under fire on Saturday for not making public possible abuses of prisoners by military intelligence officers in Iraq in 2003. Dutch daily Volkskrant had reported intelligence officers abused dozens of prisoners by hosing them with water, exposing them to bright light and blasting them with noise during heavy-handed interrogations. Kamp said on Friday he had known of possible negligent treatment of Iraqi prisoners but an investigation at the time had found no punishable acts. The leader of the opposition Labour party, Wouter Bos, said the issue showed Kamp and his officials had not understood the significance of the case. "Even if nothing happened that was wrong in terms of what international treaties require us to do, people at the ministry should have realised that it is politically very sensitive," Bos told Reuters on the sidelines of a campaign event. "We have seen what happened after Abu Ghraib -- it could produce damage to the international reputation of the Netherlands, it could produce risks to Dutch soldiers, especially those deployed in Afghanistan," Bos said. Marcel Boogers, a political scientist at Tilburg University, said the scandal was unlikely to change the outcome of the Nov. 22 election -- an expected victory for Christian Democrat Prime Minister Jan Peter Balkenende -- although it could help Labour and other left-wing parties narrow his lead. "The left-wing parties -- particularly the Socialists who were the most critical about sending troops to Iraq and Afghanistan -- could get more wind in their sails," he said. Balkenende supported the U.S.-led invasion of Iraq and sent about 1,300 Dutch troops there in 2003. He withdrew them last year as violence escalated and public opposition mounted. "During such a sensitive mission, at such a delicate time, these mistakes should never have been made," leading Dutch broadsheet NRC Handelsblad said in an editorial. "And they certainly should not have been kept quiet. That strongly tests the trust of citizens in the leadership of the military." An opinion poll released on Saturday showed Labour closing the gap on the Christian Democrats (CDA). Pollster Maurice de Hond said the CDA was on course to win 41 seats in the 150-seat parliament, down from 42 earlier in the week. Labour looked set to win 36 seats, up from 33. Forming a government is expected to be difficult. Neither the right nor the left camp appears set to win a majority, which could force the Netherlands into an uneasy coalition of CDA and Labour or a three-party coalition. (Additional reporting by Emma Thomasson)