BEIRUT (Reuters) -Leading Lebanese parties lambasted charges brought against the prime minister and three former ministers over the Beirut port explosion on Friday, highlighting the political minefield facing the investigation. The heavily armed, Shi’ite Muslim Hezbollah movement said the charges smacked of political targeting, joining a wider pushback by influential parties against the allegations of negligence made by Judge Fadi Sawan. Four months since the port blast that killed 200 people, injured thousands and destroyed entire districts, victims are still awaiting the result of the investigation. Leaders had promised it would come within days. The August explosion, one of the biggest non-nuclear blasts on record, was caused by a massive quantity of ammonium nitrate stored unsafely for years. Sawan charged caretaker Prime Minister Hassan Diab, whose cabinet quit after the blast, and three former ministers with negligence on Thursday. In a visit to Diab on Friday, Prime Minister-designate Saad al-Hariri accused Sawan, the judge leading the inquiry, of breaching the constitution. He pledged not to let anyone violate “the post of prime minister” - a seat reserved for a Sunni Muslim in Lebanon’s power-sharing system. Officials who were informed about the nitrate included Diab and President Michel Aoun, who were warned in July that it could destroy the capital if it exploded, according to documents seen by Reuters. Diab, who says his conscience is clear, has also accused Sawan of a constitutional breach. So has Ali Hassan Khalil, one of the ex-ministers, a close Hezbollah ally and senior aide to Parliament Speaker Nabih Berri. While Iran-backed Hezbollah said it supported a transparent inquiry, it rebuked Sawan’s step. “We absolutely reject the absence of unified standards that has led to what we believe to be political targeting against some people and ignoring others,” it said. The other two former ministers charged - Ghazi Zeaiter and Youssef Finianos - are also Hezbollah allies. ADVERTISEMENT Zeaiter, a parliamentary deputy from Berri’s bloc, called the charges against him “a blatant violation” that he would not remain silent about. He served as public works and transport minister in 2014, soon after the Rhosus ship carrying tonnes of the highly explosive chemical arrived at Beirut port. Finianos has yet to comment. The United States has imposed sanctions on Finianos and Khalil, accusing them of enabling Hezbollah, which Washington deems a terrorist organisation. There has been debate about whether ministers enjoyed immunity in the case. Melham Khalaf, head of the Beirut bar association, praised Sawan’s move, saying it showed courage. Former premier Najib Mikati suggested that while Diab has been charged, President Aoun, who was also informed about the presence of the dangerous material, was not. Aoun said in August he had directed the Supreme Defence Council, a grouping of security and military agencies chaired by the president, to “do what is necessary”. Reporting by Tom Perry and Ellen FrancisEditing by Mark Heinrich