Zimbabwe's president on Tuesday said "unacceptable" violence by security forces will be investigated after a days-long crackdown on economic unrest, while a doctor said the 12 documented deaths and more than 300 people wounded are likely "are just a fraction of the actual victims."President Emmerson Mnangagwa called for a national dialogue among political parties and civic leaders, even as arrests continued. He spoke after skipping a visit to the World Economic Forum in Davos, Switzerland under pressure to return home.Zimbabwe's military is in the streets for the first time since post-election violence in August killed six people. This time, people report being hunted down in their homes. More than 600 people have been arrested, most denied bail.The "army is on the forefront of orchestrating the violence," backed by ruling Zanu-PF youth gangs and police, Dr Norman Matara with the Zimbabwe Association of Doctors for Human Rights told reporters in Johannesburg.The pattern of injuries seen in the more than 300 people wounded and 12 dead suggested premeditation and training in torture, Matara said, and "we think these numbers are just a fraction of the actual victims" as some were too scared to seek treatment.Several people were dragged from their hospital beds and arrested. Some were shot in the head at close range and died. About half of those wounded were bystanders hit by stray bullets when the military opened fire on crowds. The group documented abuse of people as young as 9.Some medical professionals, accused of "trying to subvert the government" by publicising the toll, are now afraid to help victims, Matara said.Zimbabwe's president said insubordination will not be tolerated and "if required, heads will roll."He defended, however, the dramatic fuel price increase that began the unrest by making gasoline in Zimbabwe the most world's expensive. Authorities said it was aimed at easing the demand that created miles-long lines as gas stations.But Zimbabweans who had seen no improvement in the collapsed economy under Mnangagwa, who took office in 2017 after the ouster of longtime leader Robert Mugabe, lost their patience. Activists and labour leaders called for people to stay at home in protest. Others took to the streets, some looting in anger or desperation.Mnangagwa's government has blamed the opposition, despite witness accounts of security forces killing or wounding bystanders, including a 17-year-old ."Everyone has the right to protest, but this was not a peaceful protest," Mnangagwa said.The government-backed Zimbabwe Human Rights Commission said eight people were killed and criticised the use of the military and live ammunition. It said the government had not learned from the August crackdown, and should compensate "victims of military and police brutality."Mnangagwa has previously said he is open to dialogue with the main opposition MDC party, which narrowly lost both the July election and a court challenge alleging fraud. He has dismissed a government of national unity.The opposition called Mnangagwa's new call for dialogue a "gimmick to buy time.""Mnangagwa's overtures are always on Twitter. He knows where we are, yet he has chosen not to talk to us directly," MDC spokesperson Jacob Mafume said.MDC leader Nelson Chamisa said his attempts at dialogue had been "spurned and mocked" and that people must be free to talk without fear.Arrests continued. Zimbabwe Lawyers for Human Rights said police detained labour federation leader Japhet Moyo overnight, just hours after releasing him. He is charged with subversion for his role in organising the national strike along with pastor and activist Evan Mawarire.Police also detained 28 people being treated at a hospital in the capital, Harare, the lawyers' group said, calling it "very inhumane."Zimbabwe's government ordered an internet blackout in recent days as reports of abuses emerged, but the High Court on Monday ordered that full service be restored, saying only the president has the authority to order it.At Davos, Mnangagwa had planned to appeal for foreign investment and loans but faced a more difficult reception than a year ago, when optimism was relatively high about a "new Zimbabwe." Neighbouring South Africa recently turned down Mnangagwa's request for a $1.2 billion loan.South Africa is now considering a bailout for Zimbabwe "as long as it is affordable for our side," Foreign Minister Lindiwe Sisulu said. Meanwhile, President Cyril Ramaphosa again suggested that US and other sanctions on Zimbabwe be lifted or relaxed.Zimbabwe Finance Minister Mthuli Ncube told The Associated Press in Davos that "we don't need to be told by anyone that we need to do better on human rights or open up democratic space ... we need to do it for ourselves." He hopes to gain access to some $500 million in lines of credit at Davos.Zimbabwe's turmoil again brought questions about tensions between Mnangagwa and the man he had left in charge, hard-line Vice President Constantino Chiwenga, who had led the military effort to oust Mugabe.Mnangagwa and Chiwenga have dismissed reports of a rift, and they hugged upon the president's return late on Monday."This is state-sponsored violence," Dewa Mavhinga, the southern African director for Human Rights Watch, told reporters. "Mnangagwa should not pretend that the misconduct is unacceptable to his government when they are taking no action."Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.