"Forces both within and outside Egypt have been exerting efforts to abort [Egypt's] people's revolution because of the threat it poses to certain entrenched interests," Egypt's Muslim Brotherhood declared in a Monday statement.

The group went on to blame Sunday's deadly attack near Egypt's border with the Gaza Strip, in which 16 Egyptian border guards were killed, on Israeli intelligence agency Mossad.

The Brotherhood stressed that attempts to thwart Egypt's revolution and subsequent democratic transition had "escalated after the people successfully elected a new president and a new government was successfully drawn up."

The Brotherhood went on to assert that "several groups" had been plotting to hinder Egypt's progress by "instigating problems and inciting unrest with the aim of halting President Mohamed Morsi's project for national revival."

The statement added that the "Zionist media" had been quick to blame groups based in Gaza for the "terrorist attack that killed dozens of our brothers, Egyptian soldiers, in a criminal act by commandeering vehicles in an attempt to cross to the Zionist border."

The Brotherhood went on to allege that Sunday's act aimed at creating "serious problems" for Egypt on its sovereign borders, on top of the many domestic problems the country is already facing. Such counter-revolutionary activities, the group added, aim to portray Egypt's new government as a failure, derail Morsi's project for national revival, and incite conflict between Egypt's new political managers and the people and between the West Bank-based Palestinian Authority and the people of Gaza.

"This crime can be attributed to the Mossad, which has sought to abort Egypt's revolution since it first began," the statement added, pointing out that Tel Aviv had warned its citizens to leave Egypt's Sinai Peninsula only days before Sunday's attack.

The statement also referred to the Camp David peace agreement with Israel, which prohibits Egypt from making military deployments in central and eastern Sinai, and stressed the need for modifying the agreement's terms.

The Brotherhood also condemned Egypt's "failure to take any pre-emptive measures – in light of the Israeli warning – in the days leading up to the attack."

The statement concluded by calling on the Egyptian people to oppose any incitement to internal strife or violence and stand beside Egypt's president and government. The group also expressed its deepest condolences to the families of those killed in Sunday's attack.

Israel, for its part, dismissed the Brotherhood's assertions that the Mossad had played a role in the incident.

"Even the one who makes this accusation…does not believe the nonsense he is uttering," Israeli Foreign Ministry spokesman Yigal Palmor was quoted as saying by Reuters.

Egypt's Brotherhood, however, were not alone in suggesting Israeli complicity in the attack.

Hassan Nasrallah, head of Lebanese resistance group Hezbollah, and Ismail Heniya, head of Gaza-based Palestinian resistance faction Hamas, both made similar allegations.

"Israel is responsible, one way or another, for this attack, which aimed at embarrassing Egypt's leadership and creating new problems at the border in order to derail ongoing efforts to end [Israel's] longstanding siege of the Gaza Strip," Heniya declared.

Nasrallah, for his part, said that, while details of the attack "remain unclear," Israel nevertheless represented the incident's "primary beneficiary."

Earlier on Monday, the Egyptian armed forces issued a statement on state television accusing the culprits – whose identities remain unknown until present – of reaching the border area via tunnels from Gaza.

Israeli news agencies, meanwhile, attributed the attack to militants belonging to an "unknown global jihadist group."

Hamas, which has governed the Gaza Strip since 2007, strenuously denied responsibility for the incident, stressing that its security forces had since been deployed to monitor the Egypt-Gaza border.

In the immediate wake of the attack, Egyptian authorities closed the border with the Gaza Strip to all traffic.

Given Israel's five-year embargo of the besieged coastal enclave, the network of tunnels under the Egypt-Gaza border is used to bring desperately needed commodities – including food, fuel and building materials – into the strip and its roughly 1.7 million inhabitants.