CAIRO (REUTERS) - Egyptians are stocking up on food, fuel and cash ahead of protests this weekend against President Mohamed Mursi that many fear will be the most violent and disruptive this year.

Mursi's liberal, leftist and secular-minded opponents have called on Egyptians to take to the streets on June 30 - the one-year anniversary of the Islamist president's first day in office - to demand his resignation.

Street cafes, minibuses, banks, offices and grocery stores across the Arab world's most populous country have been abuzz for weeks with talk of the "June 30" protests.

Many people have started hoarding essentials, fearing a repeat of the disruption that hit business and transport during the 18-day revolt that ousted President Hosni Mubarak in 2011.

Ms Mona Kamel, a 52-year-old office secretary, said she had bought a week's worth of rice, pasta, sugar, milk, bread and cheese to see her family through any disruption.

"My neighbours, friends and colleagues are all doing this just in case," she said. "Maybe there will be curfews, maybe bakeries won't run their ovens. It's better to be prepared."

Long queues have formed at petrol stations across Cairo over the last few days, blocking thoroughfares and worsening already snarling gridlock. Some motorists said they were trying to fuel up ahead of the demonstrations.

The oil ministry on Tuesday dismissed "rumours" of fuel shortages and urged citizens not to be "misled" into hoarding petrol, the state news agency MENA reported.

But Mona Waleed, a 39-year-old local oil firm employee, said she sat in line at a petrol station for four hours on Tuesday waiting to fill up.

Waleed, who said she also made two trips to the bank this week to make sure her family of four had enough cash to last a month, said the 2011 uprising had taken many people off guard.

"This time, people are afraid and they are getting ready,"she said.

Anti-Mursi activists have been boosted by the momentum of a months-old signature drive to withdraw confidence from the president, known as "Tamarod" or "Rebel". The campaign claims to have gathered 15 million signatures, more than the number of votes Mr Mursi received in last year's presidential election.

A coalition of Mursi's Islamist supporters - including his Muslim Brotherhood - has called for counter-demonstrations to assert his legitimacy, raising the chances of violent confrontations between the two sides. The tension prompted Egypt's army to warn it may step in to impose order.

Organisers have called for marches from downtown Cairo and surrounding neighbourhoods to the presidential palace in the suburb of Heliopolis, where rival factions of Mursi's supporters and opponents have clashed in the past.

In the suburb of Nasr City, Rijan Samier, 41, said she started to worry about the potential for confrontation when thousands of Islamists flooded her neighbourhood on Friday to rally outside a local mosque in support of the president.

Some of her neighbours set up checkpoints to prevent the protesters from reaching the mosque through their street, she said, although the day passed without violence.

"Thank God, nothing happened this time," Ms Samier said.

The nervousness is also affecting suppliers.

In a working-class district near Cairo's Tahrir Square, the symbolic heart of Egypt's 2011 uprising, Youssef Sabet said he was afraid his small grocery store would be broken into if the protests turned violent.

"Whenever any problems on the street happen, they start here," Mr Sabet, 56, said. "I am running down my supplies. I've stopped bringing in new goods." Mr Sabet and other shopkeepers downtown said they would close their stores on Sunday - the first day of Egypt's working week - either to join the rallies or to protect their property.

The United States embassy said it would also close on Sunday and urged Americans to ensure they had enough supplies to make it through "an extended period" at home.

Workers at the Semiramis Intercontinental have just finished putting up a tall black steel gated fence around the five-star hotel, which overlooks Tahrir and the Nile River.

Looters broke into the hotel in January after protests marking the second anniversary of the Jan. 25 uprising, trashing the lobby and shops while riot police stood by.