Story highlights Sectarian violence has led to dozens of deaths and hundreds of injuries since last week

The clashes pit Shiite Houthi rebels against Sunni Salafi militants

The Red Cross has been unable to access Dammaj to treat wounded civilians

Yemen, the most impoverished country in the Middle East, faces growing separatist movement

Dozens of people have been killed by sectarian clashes in Yemen's northern province of Saada in the past several days, according to local officials.

In recent days, violence has escalated between Houthi rebels and Salafi militants in the city of Dammaj, with hundreds injured as a result. The Houthis are Shiites and the Salafis are Sunni Muslims.

Saada government officials and a spokesman for Salafis in Dammaj accuse Houthi rebels of firing mortars and rockets last week at Dammaj's Al-Mazraa mosque -- part of a Salafi religious institute -- in a bid to force Salafis to leave the area.

Earlier, the Houthis issued a statement accusing the Salafis of causing this conflict by transporting thousands of foreign Sunni fighters there.

The political arm of the Houthi rebel group accused the Salafis of transforming a religious center in Dammaj into a jihadist stronghold. The Houthis said they would not tolerate such a threat so close to their stronghold.

According to officials, regional Salafi figureheads have been calling for jihad against the Houthi rebels, which has raised tensions in the past several weeks.

Serour al-Wadei, a spokesman for the Salafis in Dammaj, told CNN that most of those killed by Houthis have been civilians.

The International Committee of the Red Cross expressed growing concern about the situation. In a statement released Saturday, the ICRC, which has been trying to access the area, said it was prevented again from entering Dammaj.

"There are a large number of wounded civilians in Dammaj, and the risk to them will only grow if the ICRC is denied access," the aid agency said.

ICRC teams that are about 8 kilometers (5 miles) away have been ready to respond since last week.

"We appeal for a halt to the violence and for immediate and unconditional access so that we can evacuate the wounded and deliver much-needed medical assistance," said Cedric Schweizer, head of the ICRC delegation in Sanaa, Yemen's capital.

Concerned about the escalation in violence, Yemeni Defense Minister Mohammed Nasser Ahmed ordered the dispatch of troops to Saada, on Yemen's border with Saudi Arabia, to act as peacekeepers and to deter warring factions. But so far, government efforts to end the fighting have not been fruitful.

"The ceasefire did not last, but a presidential delegation is negotiating a long-term peace agreement with both sides," a senior Defense Ministry official told CNN.

Hasan al-Hamran, a Houthi spokesman, denied the Houthis are fueling the clashes and said the government wasn't doing enough to ensure foreign jihadi fighters didn't enter the region.

"Foreigners are fighting on the side of the Salafi Sunnis in Dammaj and not Yemenis," al-Hamran said. "The government does not have authority over the Salafi religious institute, resulting in many suspected terrorists entering Saada province."

A Yemeni government official told CNN on background that the situation has been brewing for some time. The official said that for decades, Houthi supporters have complained of foreign interference coming from Dammaj, where there is a Salafi Center.

"But shelling them today is nothing more than a sign of hubris and exposes how the political map is evolving," the official added.

"The government's response has been slow because it's taking a cautious approach. The army doesn't want to be embroiled in a seventh war with the Houthis."

Insurgent Houthi rebels fought six wars with Yemen's government between 2004 and 2009. The group, which is thought to have thousands of fighters, is anti-United States and anti-Israel, and maintains its actions are taken to protect its community from government discrimination.

Yemen is the most impoverished country in the Middle East. It is facing a growing separatist movement in the country's south and is the hub for al Qaeda in the Arabian Peninsula, which many analysts believe is the most dangerous wing of the terrorist network.

Currently, the country is engaged in the National Dialogue Conference, U.N.-backed reconciliation talks aimed at drafting a new constitution and laying the groundwork for elections to be held next year.