Republicans stepped up their attacks Monday on former Secretary of State Hillary Clinton's use of a private email server and pointed to newly released messages to allege that foreign donors to the Democratic presidential nominee's family charity got preferential treatment from her department.



Congressional Republicans issued subpoenas to three technology companies that either made or serviced the server located in the basement of Clinton's New York home. The subpoenas were issued Monday by House Science, Space and Technology Chairman Lamar Smith of Texas with the support of Senate Homeland Security Chairman Ron Johnson of Wisconsin.



In a joint statement, Smith and Johnson said the move was necessary after the three companies — Platte River Networks, Datto Inc. and SECNAP Network Security Corp. — declined to voluntarily answer questions to determine whether Clinton's private server met government standards for record-keeping and security.



The subpoenas were among several developments Monday that showed a new GOP emphasis on Clinton's emails after the FBI recently closed its yearlong probe into whether she and her aides mishandled sensitive government information that flowed through her server. The FBI recommended against criminal charges.



The State Department is now reviewing nearly 15,000 previously undisclosed emails recovered as part of the FBI investigation. Lawyers for the department told U.S. District Court Judge James E. Boasberg on Monday that they anticipate processing and releasing the first batch of these new emails in mid-October, raising the prospect that new messages sent or received by Clinton could become public just before November's election.



Boasberg is overseeing production of the emails as part of a federal public-records lawsuit filed by the conservative legal advocacy group Judicial Watch. Representing the State Department, Justice Department lawyer Lisa Olson told the judge that officials do not yet know how many of the emails are work-related, rather than personal.



Clinton, who was secretary of state from 2009 to 2013, had claimed she deleted only personal emails prior to returning more than 55,000 pages of her work-related messages to the State Department last year. The department has publicly released most of those emails, although some have been withheld because they contain information considered sensitive to national security.



The thousands of previously undisclosed Clinton emails obtained by the FBI came from the accounts of other people she communicated with or were recovered through the bureau's forensic examination of her old server.



Clinton campaign spokesman Brian Fallon reiterated Monday that Clinton provided all the work-related emails she had "in her possession" when the State Department asked for copies in 2014. "If the State Department determines any of them to be work-related, then obviously we support those documents being released publicly as well," he said.



Olson said the department earlier this month received seven discs containing "tens of thousands" of emails Clinton sent or received during her tenure as the nation's top diplomat. The first disc, labeled by the FBI as containing nonclassified emails not previously disclosed by Clinton, contains about 14,900 documents, she said.



She said it was "extremely ambitious" for the agency to complete its review and begin releasing the first batches of emails to Judicial Watch by Oct. 14, given the volume of messages.



Also Monday, Judicial Watch released 20 previously undisclosed email exchanges involving Clinton that were turned over by her former deputy chief of staff, Huma Abedin.



Among them is a June 23, 2009, message to Abedin from Doug Band, a longtime aide to former President Bill Clinton who then was an official at the Clinton family's charitable foundation. Republicans charge that donors to the foundation, including foreign governments and corporations, got preferential treatment from the State Department while Hillary Clinton was secretary of state.



Band sought to arrange for the crown prince of Bahrain to meet with Hillary Clinton while the prince was visiting Washington. "Good friend of ours," Band wrote to Abedin, one of Clinton's closest aides.



Crown Prince Salman had in 2005 made a $32 million commitment to the Clinton Global Initiative, a program run by the foundation.



In later emails Abedin confirmed that Clinton would meet with the prince. Copies of Clinton's calendar obtained by the AP confirm the meeting occurred in her State Department office on June 26, 2009.



State Department spokesman Matt Toner said Monday there was nothing improper or unusual about the messages with Clinton Foundation staff.



"There was no impropriety," Toner said. "This was simply evidence of the way the process works in that, you know, any secretary of state has aides who are getting emails or contacts by a broad range of individuals and organizations."



In a statement, the government of Bahrain said the $32 million pledge was in support of a scholarship program for young men and women from the Persian Gulf kingdom who attend universities in Europe and North America. The purpose of Salman's 2009 visit with Secretary Clinton was wholly unrelated, according to the statement.



"As deputy head of state, the crown prince has and will continue to meet with U.S. officials to address matters of mutual interest in the future," the statement said.