US conglomerate Comcast said Thursday it received 24,698 law enforcement requests for customer data in 2013, plus some for national security reasons.

The company, which published its first "transparency report," followed guidelines of an agreement with US authorities which allow only a range of numbers to be reported on national security requests.

Comcast, which operates the largest US cable broadband service and owns NBCUniversal, said the number of orders from the secret Foreign Intelligence Surveillance Court were between zero and 999 in the first six months of 2013.

Internet companies are required to delay these reports on secret court orders for at least six months, so only the period up to June 30 is covered.

Comcast also reported the same range for the number of 2013 "national security letters," which are generally from the FBI as part of an investigation related to potential terrorism.

The nearly 25,000 requests from law enforcement include subpoenas, court orders and wiretaps.

"By law, we are required to respond to valid government requests. Some of the law enforcement requests also involve emergency disclosures to prevent imminent risk of death or serious physical injury," Comcast deputy general counsel and chief privacy officer Gerard Lewis said in a blog post.

"Protecting our customers' privacy is among our highest priorities and is required by the Cable Act, one of the strictest federal privacy laws. So with every request, whether it is from a local police department or the Federal Bureau of Investigation, we make sure it complies with applicable legal standards before we respond with any information."

US authorities, facing legal challenges and a public campaign for more transparency, agreed last month to allow some information on national security requests but only in broad ranges.

The deal came in response to pressure from the tech sector following leaked National Security Agency documents outlining vast surveillance of online and phone communications.

Comcast has announced a tie-up with Time Warner Cable which would boost its position as the largest US cable firm. The deal is being reviewed by US antitrust officials.