Israel expects a "grave erosion" in its peace agreement with Egypt and is even preparing for the possibility of the historic deal collapsing altogether, a Cabinet minister said Wednesday, in the first official assessment of the unrest rocking Israel's southern neighbor. The comments by Matan Vilnai, Israel's minister for civil defense and a retired military general, reflected the government's grave concerns that Egypt's Muslim Brotherhood could make major gains, and even win, upcoming elections in Egypt. "The picture is quite clear. We've been saying it for months. Apparently what we call the Muslim Brotherhood ... will ultimately be the majority in all the (Egyptian) institutions," Vilnai told Israel's Army Radio station. The Brotherhood is the most organised political group in Egypt and it is widely expected to make a strong showing in the election. Estimates of how much of parliament it will win have ranged from 20 per cent to nearly 50 per cent. Other Islamic fundamentalist parties are also running, raising the possibility that they could form a majority, though there are also divisions among the religious parties. But amid Egypt's stormy politics, it is unclear how much leeway the Brotherhood will have after elections. It is under heavy pressure to work with liberal groups, and the military is likely to dominate the upcoming government. Brotherhood leaders have said they do not seek to outright end the 1979 peace accord with Israel. Like many liberal and secular factions, they say they want amendments in the deal, particularly to change provisions that bar the Egyptian military from deploying in the Sinai Peninsula, near the border with Israel. Many in Egypt see that provision as a blow to national pride and as fueling insecurity in the desert territory. Vilnai said he did not expect the peace agreement to unravel immediately since Egypt's post-revolution government will be preoccupied with domestic issues. "But once the regime stabilises, as we expect it to do, we expect that there will be a grave erosion of this agreement. And we have to prepare for such a situation," Vilnai said. Egyptian police have been clashing with anti-government protesters in Cairo for five days, killing nearly 40 people. Tens of thousands of protesters have jammed Cairo's Tahrir Square, urging Egypt's military government to step down in favor of an interim civilian council. Authorities insist the violence will not prevent the beginning of parliamentary elections on Monday. The Brotherhood, eager to ensure that elections take place, has refused to join the new demonstrations, which have been led by liberal and secular activists. The peace agreement with Egypt is a cornerstone of Israeli security. The agreement, the first with an Arab nation, has kept a once-volatile border quiet for three decades and allowed the military to divert resources to deal with Palestinian militants in the West Bank and Gaza Strip, and Hezbollah guerrillas across Israel's northern border in Lebanon. Israeli defense officials confirm the military has already begun preparing for a number of scenarios, including the possibility of the peace agreement being canceled. The officials spoke on condition of anonymity because they were discussing a sensitive security issue, and it was not clear whether the preparations are limited to discussions or include actual drills or troop deployments. The Israeli army did not immediately respond to a message seeking comment. The army declined comment on any preparations it may be making. But it denied a report in an Israeli newspaper that the military chief, Lt. Gen. Benny Gantz, raised the possibility of peace collapsing in a briefing to top officials on Tuesday.