KYIV and Thomas CaldwellLONDON -- A Ukrainian woman has been detained by Ukraine’s Security Service in connection with an apparent plot to attack President Volodymyr Zelenskyy, the service said on Monday.

The woman, who is from Mykolaiv but was not publicly named, was being questioned, officials said. She had been part of a plot aimed at assassinating Zelenskyy during his visit last week to Mykolaiv, a southeastern city near the front, officials said.

Law enforcement officials said she had been caught "red-handed" as she handed info to the Russians.

She allegedly was passing information on to Russian forces about Zelenskyy's location, including a full itinerary of the president's visit to the region. The Russians would have then ordered an airstrike to assassinate him, Ukrainian officials alleged.

Investigators learned of the woman's alleged plans ahead of the visit and Zelenskyy took “additional security measures” while in the area, security officials said.

“The Ukrainian Security Service continued to document the criminal actions of the enemy accomplice in order to obtain new data about her Russian ‘curators’ and the tasks received,” officials said in a Monday statement written in Ukrainian.

As investigators gathered additional info, they found that the woman had been locating Ukraine’s defense systems and ammunition warehouses throughout the Ochakov region, they said. She traveled to the region and photographed sites, officials said.

The woman had allegedly been planning to share that info with Russia for “a new massive air strike” in the region.

Zelenksyy said he was briefed on "the struggle against traitors in Ukraine" during his daily conference call with Ukrainian leaders on Monday.

ABC News' Joe Simonetti contributed to this report.