Israeli Foreign Minister Avigdor Lieberman on Wednesday brushed off world criticism and demands for an investigation into the deaths of two Palestinian youths killed by Israeli forces last week. "I reject any demand" for an international investigation, he told reporters on a tour of the West Bank settlement of Ariel. "Such an incident will be investigated regardless of any demand," he remarked, denouncing world criticism of the incident as "hypocrisy". His remarks came a day after calls by Washington and a top UN official for an immediate investigation into the circumstances of the two deaths after video footage emerged which appeared to show the shooting was unprovoked. The closed-circuit footage, released on Wednesday by the NGOs Defence For Children International and B'Tselem, appeared to show separate incidents in which two youngsters were shot as they walked down the same street near Ramallah as Palestinians marked the 66th anniversary of the Nakba or "catastrophe" of Israel's creation. Although clashes were taking place in the area on that day, there is no visible evidence of ongoing unrest in the footage. The Palestinian leadership accused Israel of their "deliberate execution". But the Israeli army dismissed the footage as having been "edited", and said it was investigating the incident. Late on Wednesday, US State Department spokeswoman Jen Psaki said Washington expected the Israeli government "to conduct a prompt and transparent investigation to determine the facts surrounding this incident". And Oscar Fernandez-Taranco, assistant UN secretary general for political affairs, called for an "independent and transparent" probe, He said it was "of serious concern that initial information appears to indicate that the two Palestinians killed were both unarmed and appeared to pose no direct threat". But Lieberman brushed off such calls. "We don’t need an American demand" to launch an investigation, he said. "We will do it as part our commitment to the Israeli army’s moral code." Israel has said that border police were operating in the area at the time to try to quell a violent demonstration by about 150 Palestinians, and denies using live bullets.   But the Palestinians say the youths were unarmed and posed no threat, accusing Israel of using "excessive and indiscriminate violence". In a separate development, the UN agency for Palestinian refugees on Wednesday published figures showing "a sharp increase" in the number of Palestinian refugees killed and injured by Israeli forces since the beginning of 2013. According to UNRWA, there has also been a big increase in the numbers of those injured by live ammunition in 2014, with 43 wounded this year compared with 10 in the same period in 2013.