In a report published on Sunday, the US newspaper reported that the Egyptian military was the undisclosed buyer of $23 million worth of rocket-propelled grenades from North Korea in 2016.
The Post cited US officials and Western diplomats familiar with the findings who remained anonymous.
But the Egyptian foreign ministry denied the report on Monday. In a statement sent to AFP, spokesman Ahmed Abu Zeid "categorically denied what the (Washington Post) report mentioned regarding Egypt being the destination for the shipment.
"The sanctions committee report did not indicate that the shipment was destined for Egypt," he added, referring to a UN report mentioned in the Post story.
The United States had warned Egypt in August 2016 that a North Korean vessel named Jie Shun, under the Cambodian flag, was headed toward the Suez Canal.
The ship, the Post reported, was run by a North Korean crew and had "an unknown cargo shrouded by heavy tarps".
When it reached the Suez Canal, customs agents boarded the ship and found more than 24,000 North Korean rocket-propelled grenades, the newspaper reported. The report said a UN investigation found that Egypt was the original buyer of the shipment, which Egypt denies.
"The shipment that was confiscated was not destined for Egypt," said Abu Zeid.
"Egyptian authorities indeed intercepted a ship flying the Cambodian flag before it entered the southern entrance of the Suez Canal, following information that it was carrying anti-tank rockets from North Korea in violation of (UN Security Council) sanctions.
"Egyptian authorities indeed confiscated the shipment and destroyed it in the presence of a team of experts from the 1718 committee overseeing the UNSC sanctions on North Korea," said the foreign ministry spokesman.
Abu Zeid added that "the head of the UNSC North Korea sanctions committee has lauded Egypt's efforts."
The Post reported that the officials said the incident "was one of a series of clandestine deals" that led President Donald Trump's administration to freeze or delay about $300 million in military aid to Egypt this year.
The United States projected arms dealing is the last resort for the beleaguered regime of Kim Jong Un, struggling under the weight of the sanctions levied against his country.
North Korea is believed to be dealing weapons to pariah regimes in Iran, Myanmar, Cuba, Syria and Eritrea, as well as to terrorist organizations.
Arms dealing has turned out to be a steady source of income for the despotic regime, which uses flags of other nations to mask its shipments and covers the weapons underneath cargos of sugar or iron ore.