(CNN) -- A Somali official denied reports that Ethiopian troops had crossed into the country to help battle Islamist rebels trying to take control of the nation's capital.

"I can confirm to you that no Ethiopian soldier has come to this town of Dolo," said Gov. Abdifatah Gesey of the Bay region in Somalia's southwest. "The reports which are saying so are mere rumors."

Gesey spoke to CNN on the phone Friday from Dolo, a Somali town bordering Ethiopia.

Dolo is under the control of government forces, the governor said.

Somali government officials warned Friday that Islamist Al-Shabaab rebels may intensify attacks against civilians and security forces over the Ramadan period.

Abdirahman Omar Osman, the Somali minister of information, said government and African Union forces are prepared for any assaults. He urged residents to be vigilant and remain indoors.

African Union forces mostly from Uganda and Burundi are helping the Somali government fight the militants.

Al-Shabaab rebels have killed at least 70 civilians and wounded 200 others this week, the minister said.

In return, government forces have killed 25 fighters since Monday, according to Osman.

The United States considers Al-Shabaab, which is al Qaeda's proxy in the country, a terrorist organization.

Al-Shabaab is waging a war against Somalia's government in an effort to implement a stricter form of Islamic law known as sharia.

Somalia has not had a stable government since 1991, and fighting between the rebels and government troops has escalated the humanitarian crisis in the famine-ravaged country.

Source: CNN