Aides to US President Joe Biden have discovered at least one more batch of classified documents in a location separate from a think tank office he used after serving as vice president, news outlets reported on Wednesday, citing unnamed sources. Biden aides have been searching for additional classified materials that might be in other locations since a set of classified documents was found in November at the Washington-based think tank, according to a report in NBC News. The NBC News report said the classification level, number and precise location of the additional documents was not immediately clear. It also said it was not clear when the additional documents were discovered and whether the search for any other classified materials Biden may have from his time as vice president is complete. The reports come two days after a White House lawyer said classified documents from Biden's vice presidential days had been discovered in November by the president's personal attorneys at the Penn Biden Center for Diplomacy and Global Engagement think tank. Biden's attorneys discovered fewer than a dozen classified records inside the office at center, and informed the US National Archives of their discovery, turned over the materials, and said they were cooperating with the Archives and the Justice Department. The president said on Tuesday he and his team were cooperating fully with a review into what happened.