Abdifatah Abdikadir, a resident, said he saw hundreds of troops in the neighbourhoods on Sunday where the protests had erupted.
"Around 500 government troops have been deployed in the streets. I also saw about 15 technicals mounted with heavy machine guns," he said, referring to pick-ups with guns.
A senior security source said the troop deployment was aimed at preventing further unrest.
"We have deployed so many troops in order to prevent any problems. The city is calm, there is no problem at all," he said.
The source also said that an Islamic courts fighter had been killed overnight.
"An Islamist member of Ifka Halanka Islamic courts was killed last night. We don't know whether this is a targeted killing or he was killed by thugs ... He was not a senior figure."
In the south central town of Baladwayne on Sunday, hundreds of people took to the streets calling for Ethiopian troops to free a military commander detained for refusing to hand over an Islamic courts fighter, a resident said.
European and African diplomats, as well as the Somali government, want an African peacekeeping force - endorsed by the United Nations before the war - to be deployed as soon as possible to fill a security vacuum while the government builds up its own military.
Abdullahi Yusuf, the Somali president, asked Addis Ababa to train Somali forces, Ethiopian state television said on Saturday, after the Somali leader met Meles Zenawi, the Ethiopian prime minister.
|Crowds hurled stones and burnt tyres during|
Saturday's protests in Mogadishu [Reuters]
Meles has said his troops will leave the Horn of Africa nation in a few weeks and it was not clear if the training request would extend their stay.
Any prolonged Ethiopian deployment would be likely to anger many Somalis who resent the presence of soldiers from their militarily superior neighbour, which has invaded Somalia numerous times in what Addis Ababa calls defensive missions.
Islamic courts 'remnants'
Abubakr al-Qirbi, Yemen's foreign minister, meanwhile, has said some Islamic courts leaders had arrived in Yemen, creating an opportunity for talks with Somalia's interim government.
News of their presence coincided with a visit on Saturday to the Yemeni city of Aden by Jendayi Frazer, the US assistant secretary of state for African affairs, who called for dialogue between Somali groups, including "remnants" of the Islamic courts.
The Islamic courts, which fled their last stronghold on January 1, after controlling much of southern Somalia for six months, have pledged to fight on.
Residents say they have melted into the hills in Somalia's remote southern tip where Ethiopian and government forces are searching for them.
Kenya has sent troops to seal its frontier and about 23 suspected fighters, including foreigners, have been arrested, according to a local police official.