Harare - Zimbabwe's opposition Movement for Democratic Change on Monday called on SADC to intervene after at least 20 people were arrested during clashes between taxi drivers and police in the capital Harare."Zimbabwe is burning. The region cannot fold its hands while the situation is worsening in a member state," said party spokesperson Obert Gutu.The state broadcaster quoted police spokesperson Charity Charamba as saying that 20 arrests had been made and 10 commuter omnibuses impounded in the clashes on Monday morning, which centred on the Epworth, Mabvuku and Ruwa areas.Violent protests in the border town of Beitbridge on Friday saw a government warehouse burned down, a fastfood outlet looted, traffic lights vandalised and rocks placed on roads.These scenes were unusual in a country largely cowed by three and half decades of rule by President Robert Mugabe. Criticism of the longtime ruler, now 92, was not tolerated: in fact, a young former Zanu-PF official, Acie Lumumba, who last week used the F-word against Mugabe handed himself over to police on Monday, it was reported.'Retaliatory measures'But new tight controls on imports of basic goods like jam, mayonnaise, body lotion and weaves appeared to have been the final straw. With formal employment likely to represent only 10% of all jobs, many Zimbabweans depended on small scale trading to make ends meet.Harare economist Vince Musewe tweeted this weekend: "Import ban wrong policy to stimulate local production until [agriculture] sector is revived and industrial capacity increased. Is that difficult to fathom?" The Movement for Democratic Change said the government had invited "retaliatory measures" by pushing ahead with the regulations. Mugabe's government insisted they would stay in place. Local Government Minister Saviour Kasukuwere at the weekend slammed "people burning down structures because they failed to buy chilli in South Africa", in a reference to the Beitbridge unrest, the Herald daily reported.Video footage posted to social media on Monday afternoon appeared to show riot police beating and hunting down protesters in Epworth suburb, one of the morning's flashpoints.