NEW YORK - Israel believes Hizbullah now has an arsenal that includes 10,000 long-range rockets and 20,000 short-range rockets in southern Lebanon, UN Secretary-General Ban Ki-moon told the Security Council in a report on Monday. While Ban's report did not confirm Israel's claim, the UN chief reiterated his concern about Hizbullah's public statements and persistent reports pointing to breaches of a UN arms embargo, which bans weapons transfers to the Islamic group. Ban also expressed concern over "the threats of open war against Israel" by Hizbullah leader Hassan Nasrallah. Nasrallah accused Israel of trying to start a new war by assassinating the group's operations chief and warned it would be a battle the Jewish state would lose. Israel has denied involvement in the February 12 car bombing in Damascus that killed Imad Mughniyeh. "We thought it reflected to a certain extent the situation on the ground," said Israeli Ambassador to the UN Dan Gillerman. "It reflected the worry that the UN has over the rearming of Hizbullah and the fact that resolution 1701 isn't implemented fully. I think it was a fairly factual and balanced report." Gillerman said he had spoken to the secretary-general at great length before the report was issued. "He is very sensitive to our [captive] soldiers, [Eldad] Regev and [Ehud] Goldwasser, and is trying as hard as he can to help on this matter," he said. "He is very aware of the fragility and vulnerability of the situation, which is dangerously explosive and which poses dangers to his own troops. On the whole, [the report is] fair and balanced." The secretary-general's report focused on the implementation of the UN cease-fire resolution that ended the 34-day war between Israel and Hizbullah in August 2006. The resolution reiterates a call for the disarming of all armed groups and bans arms transfers to them. "Reports of Hizbullah rearming are a cause of great concern, posing serious challenges to the sovereignty, stability and independence of Lebanon," Ban said. He told the council that he continued to believe that the disarmament of Hizbullah and other armed groups must be part of a Lebanese-led political process that would fully restore the government's authority throughout the country. He expressed regret "that the persistent deterioration of the political climate and the prolonged deadlock" over the election of a new Lebanese president have made it impossible to deal with the disarmament issue. In his last report to the council in late October, Ban alleged that Hizbullah had rearmed with new long-range rockets capable of hitting Tel Aviv and tripled its arsenal of C-802 land-to-sea missiles since the 2006 war. He also drew attention to alleged breaches of the arms embargo and the transfer of sophisticated weapons from Iran and Syria - both strong backers of Hizbullah - across the Lebanon-Syria border. Syria has disputed the claim and countered that the allegations of weapons smuggling were motivated by political rather than security considerations, Ban said, but Hizbullah's leaders have admitted on several occasions that their military capacity has been replenished since the war with Israel. "I, therefore, remain concerned that this border remains vulnerable to such breaches, which would represent serious violations of the resolution and constitute a significant threat to the stability and security of Lebanon," he said. "All member states in the region, in particular the Syrian Arab Republic and the Islamic Republic of Iran, have a key responsibility in this regard," the secretary-general said. "Such violations risk further destabilizing Lebanon and the whole region." After the 2006 war, a beefed-up UN force was stationed in Lebanon, south of the Litani River, partially to keep Hizbullah from smuggling weapons into the area. In Monday's report, Ban said Israel maintained that Hizbullah "is significantly rebuilding its military presence" inside the UN's area of operations, and on occasion had provided the UN with information. But he said UN and Lebanese forces had found no evidence so far of new infrastructure, though their operational activities were occasionally closely monitored by unarmed civilians. Israel also contends that Hizbullah has continued to construct new facilities and carry out training north of the Litani River and in the Bekaa Valley, where the government of Lebanon has exclusive responsibility for security, Ban said. "Hizbullah has not challenged allegations regarding the development of military facilities north of the Litani River and has publicly announced that it will use its arsenal against Israel if provoked," he said. Israel claims Hizbullah has also adapted its tactics to the UN presence south of the Litani River and can fire rockets at Israel, Ban said. "In addition to information provided in previous reports, the government of Israel states that Hizbullah's arsenal includes some 10,000 long-range rockets, in addition to some 20,000 short-range rockets, deployed both north and south of the Litani River," the secretary-general said. He said Hizbullah denied transferring weapons south of the Litani River in violation of the 2006 resolution. Before the war, Israel estimates, Hizbullah had 13,000 rockets deployed. During the war, Hizbullah bombarded Israel with nearly 4,000 rockets. The rockets struck as far south as Hadera. In the report, Ban also expressed concern that Israeli air violations continued unabated "without any regard for the levels of tension and anger that these actions trigger on the ground." He reiterated his urgent call for Israel to provide detailed information on the cluster munitions it fired during the war, saying the information provided last month was "of very limited value." Gillerman said he had made it clear to the secretary-general that the overflights were conducted for "security and intelligence-gathering." "Without them, we would not have been able to destroy long-range missiles," said Gillerman. "As long as the arms supply continues and soldiers are held, we have to continue. I don't think he agrees, but he got the message." AP contributed to this report.