U.S. President Donald Trump on Saturday accused former President Barack Obama of wiretapping him in October during the late stages of the presidential election campaign, but offered no evidence to support the allegation. Obama's office did not immediately respond to a request for comment from Reuters. The White House also did not respond to a request to elaborate on Trump's accusations. Former Obama adviser Ben Rhodes strongly denied Trump's allegations. "No president can order a wiretap. Those restrictions were put in place to protect citizens from people like you," Rhodes wrote on Twitter. In response to Trump's tweet about a lawyer making a "great case," Rhodes responded: "No. They couldn't. Only a liar could do that." A Trump spokeswoman said the Republican president is "having meetings, making phone calls and hitting balls" at his golf course in West Palm Beach. In one of the Tweets, Trump said the alleged wiretapping took place in his Trump Tower office and apartment building in New York, but there was "nothing found." Trump's administration has come under pressure from Federal Bureau of Investigation and congressional investigations into contacts between some members of his campaign team and Russian officials during his campaign. House Democratic Leader Nancy Pelosi ridiculed Trump's assertions. "The Deflector-in-Chief is at it again. An investigation by an independent commission is the only answer," she wrote on Twitter Saturday. Several Republicans on Saturday again urged an investigation into a series of intelligence-related leaks. Obama imposed sanctions on Russia and ordered Russian diplomats to leave the United States in December over the country's involvement in hacking political parties in the Nov. 8 U.S. presidential election. On Saturday, Representative Eric Swalwell, a Democrat who is a member of the House Intelligence Committee, told Fox News that Trump "is not credible when it comes to talking about Russia."