Egypt has accused Gaza-based Hamas militants of training Egyptian Islamists to carry out bombings and other acts of terrorism in the Sinai peninsula.
In the neighboring Gaza Strip Thursday, Hamas rejected the accusations, calling them "completely incorrect."
The latest Egyptian allegations, aired on state television, come a day after authorities reported twin Sinai car bombings near the Gaza border that killed six Egyptian soldiers and wounded 17 other people. No one has claimed responsibility.
Those blasts targeted a military checkpoint in the Egyptian border town of Rafah, further straining political tensions already frayed by the July ouster of Egypt's Islamist president Mohamed Morsi.
The televised accusations include Egyptian charges that the military wing of Hamas trained Sinai-based Islamists in bomb making and car bombings. It also accused Hamas of supplying local militants with 400 landmines.
Last week, Egypt launched what it called its biggest operation against Sinai terrorists in years. Officials later said about 20 militants had so far been killed in the operation near the Gaza Strip.
The Sinai surge in militant activity corresponds to a security vacuum first observed after former president Hosni Mubarak was driven from power in 2011.
Interim government officials say militant attacks, including last week's failed assassination attempt on Egypt's interior minister, have further surged since the military ousted Mr. Morsi and placed him in detention.