WASHINGTON (AP) — U.S. officials tell The Associated Press that the two emails on Hillary Rodham Clinton's private server that an auditor deemed "top secret" include a discussion of a news article detailing a U.S. drone operation.

There was also a separate conversation that could point back to highly classified material in an improper manner or merely reflect information collected independently, U.S. officials who have reviewed the correspondence told The Associated Press.

The sourcing of the information could have significant political implications as the 2016 presidential campaign heats up. Clinton, the front-runner for the Democratic nomination, agreed this week to turn over to the FBI the private server she used as secretary of state, and Republicans in Congress have seized on the involvement of federal law enforcement as a sign that she was either negligent with the nation's secrets or worse.

On Monday, the inspector general for the 17 spy agencies that make up what is known as the intelligence community told Congress that two of 40 emails in a random sample of the 30,000 emails Clinton gave the State Department for review contained information deemed "Top Secret/Sensitive Compartmented Information," one of the government's highest levels of classification.

The two emails were marked classified after consultations with the CIA, which is where the material originated, officials said.

The officials who spoke to the AP on condition of anonymity work in intelligence and other agencies. They wouldn't detail the contents of the emails because of ongoing questions about classification level. Clinton did not transmit the sensitive information herself, they said, and nothing in the emails she received makes clear reference to communications intercepts, confidential intelligence methods or any other form of sensitive sourcing.

The drone exchange, the officials said, begins with a copy of a news article that discusses the CIA drone program that targets terrorists in Pakistan and elsewhere. While a secret program, it is well-known and often reported on. The copy makes reference to classified information, and a Clinton adviser follows up by dancing around a top secret in a way that could possibly be inferred as confirmation, they said. Several officials, however, described this claim as tenuous.

But a second email reviewed by Charles McCullough, the intelligence community inspector general, appears more suspect. Nothing in the message is "lifted" from classified documents, the officials said, though they differed on where the information in it was sourced. Some said it improperly points back to highly classified material, while others countered that it was a classic case of what the government calls "parallel reporting" — different people knowing the same thing through different means.

The emails came to light Tuesday after Sen. Chuck Grassley, R-Iowa, reported that McCullough found four "highly classified" emails on the unusual homebrew server that Clinton used while she was secretary of State. Two were sent back to the State Department for review, but Grassley said the other two were, in fact, classified at the closely guarded "Top Secret/SCI level."