(Adds background, quote from Saudi foreign minister) JEDDAH, Saudi Arabia, Aug 12 (Reuters) - Saudi King Abdullah congratulated Haider al-Abadi on his appointment as Iraq's new prime minister, the state news agency SPA reported on Tuesday, in a sign of Riyadh's eagerness to see the departure of his predecessor Nuri al-Maliki. While the king routinely issues **tes of congratulation to newly elected or appointed leaders, his message to Abadi is especially significant because of the political uncertainty in Iraq, where Maliki has refused to step aside. Top Saudi officials have frequently lambasted Maliki as being a tool of Iran and ruling only on behalf of the Shi'ites. Earlier this year Maliki accused Riyadh of funding Sunni Muslim insurgents in Iraq's western Anbar province, a charge Saudi Arabia vehemently rejected.