Sudan's largest opposition groups have called for a fresh wave of protests to demand that President Omar al-Bashir step down, as the longtime ruler made another attempt to stem popular discontent by promising wage hikes and appealing to patriotism.

In a joint statement on Thursday, four groups called for nationwide protests on Friday and a march on the president's Nile-side palace on Sunday.

They also called for a march on parliament in Khartoum's twin city of Omdurman to present a petition demanding that the 74-year-old general-turned-president step down.

The demands are likely to turn up the pressure on al-Bashir to find a way out of the crisis. Sudan has seen two weeks of violent street protests, with dozens killed.

During Thursday's anti-government protests in Port Sudan, Sudanese security forces fired tear gas at protesters who were trying to deliver an anti-government petition to the local headquarters of President Omar al-Bashir's ruling National Congress party, a witness told Reuters news agency.

More than 200 people took part in the demonstration, which broke up before the protesters reached the building.

The protests were initially sparked by steep price hikes, a fuel shortage and a liquidity crunch that forced authorities to place a ceiling on bank withdrawals and led to long lines at ATMs.

Authorities have declared emergency laws and a nighttime curfew in some cities. Classes have been suspended at schools and universities across much of Sudan, a country of 43 million people.

On Thursday, al-Bashir touted improvements to Sudan's infrastructure since he seized power in a 1989 coup. He said international sanctions targeting Sudan, which is on the US list of countries sponsoring terrorism, have inhibited economic progress.

New policies

"We are subjected to both war and sanctions, but Sudan has remained steadfast," he said in a speech before representatives of pro-government unions in Khartoum.

He promised wage increases starting this month, an overhaul of the health system and improved benefits for pensioners, without elaborating.

"The Sudanese people deserve more than this. They deserve to lead a life of dignity," he said. "We could have taken the near and easy path and sold our independence, dignity in return for some dollars ... but, together, we will come out stronger from this crisis."

Al Jazeera's Hiba Morgan, reporting from Sudan's capital Khartoum, said that it's unclear whether his call to raise wages for civil servants will have an impact on the protests that are being planned for Friday.

"He said that the lowest-tier civil servant will be getting an extra $10 a month starting next month and the highest-earning civil servant will be earning an extra $50," Morgan said.

"People were saying that the issue isn't the economy, the issue is how he's been running the country for the past 29 years.

"He seems to be blaming everyone but himself and his policies. He keeps saying he will try to introduce new policies. He says that the budget for 2019 is trying to reduce inflation which is at 70 percent at the moment, one of the highest in the world," Morgan said.

Al-Bashir spoke of his humble upbringing and recalled a time in his youth when he fell and broke his front tooth while working on a construction site.

"They gave me saltwater to rinse my mouth and I continued working... Let no one talk to me about poverty and suffering because I lived them," he said, adding that he never replaced the missing tooth because he wanted to remember the hardships he had endured.

The crowd responded with chants of "March on, march on, oh Bashir!" and "God is greatest!"

Sudan's economy has stagnated for most of al-Bashir's rule. He has also failed to unite or keep the peace in the religiously and ethnically diverse nation, losing three-quarters of Sudan's oil wealth when South Sudan seceded in 2011 following a referendum.

A year earlier, he was indicted by the International Criminal Court for genocide in Sudan's western region of Darfur.