"We are outraged," Russian Deputy Foreign Minister Sergey Ryabkov said in a statement posted on the Russian Foreign Ministry website, adding the claim may have been the work of the US State Department seeking "revenge" for the collapse of talks between the two counties to address the situation in Syria.
Russia's denial came after a report two days ago
by Radio Free Europe/Radio Liberty that the diplomats -- a man and a woman who were not senior officials -- allegedly had their drinks spiked with a date-rape drug while attending a United Nations convention on corruption last November. The report, attributed to anonymous sources, said the State Department quietly protested the incident to Russian officials.
The story also said one of the diplomats had been treated at a "Western medical clinic" - which Russia said was not true.
"A probe conducted by Russia revealed that at the time no Americans had sought treatment at any St. Petersburg medical institutions," Ryabkov said. "If, alternatively, they had just been boozing at a hotel bar, they have only themselves to blame."
He added that Russian investigators at the time responded "promptly" to information from the US Embassy, but that when they asked for "more specificity to their complaints" the Americans did not respond, not even to provide the names of the "victims."
While the State Department has declined to comment on the report, US officials have expressed concern generally over the treatment of American diplomats in Russia.
"We remain troubled by the way our diplomatic and consular staff have been treated over the past two years," State Department spokeswoman Elizabeth Trudeau told reporters this week.
"We have raised our concerns at the highest levels," she added. "In particular, the harassment and surveillance of our diplomatic personnel in Moscow by security personnel and traffic police has increased significantly. As we've said before, we find this unacceptable."
In his statement, Ryabkov also cited what he called a "clear increase" in the number of US attempts to "recruit" Russian diplomats posted in the US including "threats against the well-being of family members."
Earlier this week, the US suspended ongoing talks with Russia over ways to achieve a lasting cessation of hostilities in Syria.
Secretary of State John Kerry blamed the impasse on Russian support for Syrian President Bashar al-Assad and the regime's ongoing assault against the city of Aleppo.