Police believe they have broken up a major gang of robbers with the arrest of 42 people thought to be behind more than 60 armed robberies and break-ins at businesses and construction sites.

The gang is believed to have been headed by three men. The three, a 35-year-old surnamed Chen from Anhui province, a 44-year-old named Zhao also from Anhui, and a 39-year-old named Liu from Henan, were taken into custody on Dec 13.

Their alleged gang was rounded up in a series of arrests on the same day in locations including the capital's Fengtai and Daxing districts and Anhui province.

Officers also seized allegedly stolen goods that included computers, vehicles and bundles of cables.

Police believe the gang targeted small- and medium-sized businesses in the capital's districts of Chaoyang, Daxing and Fengtai as well as in the city of Tianjin and in Hebei province, said Zi Xiangdong, spokesman for the Beijing Municipal Public Security Bureau.

"They usually climbed over the walls or entered businesses by breaking down doors or digging tunnels before hauling off safes and construction materials," Zi said.

Sometimes they used violence to intimidate people working in the companies they targeted.

Officers believe the robberies and break-ins netted the gang stolen goods worth more than 10 million yuan.

The gang was rounded up after a robbery at a company in Daxing district left clues that led police to the suspects.

In that incident, more than 10 disguised men carrying knives and clubs broke into the office of a company at about 2 pm on Nov 3. Security guards and accountants in the building at the time were tied up before the gang ransacked the offices.

They hauled off 10 computers, two cellphones and 5,600 yuan in cash. They also took a safe that contained 2,000 yuan.

In some cases, Zi said, the gang opened safes on location but other times they hauled them away so they could be opened elsewhere.

A special team of criminal investigators identified about 20 jobless men who met in a small restaurant in Fengtai district and left from the restaurant to carry out their robberies, usually between 11 pm and 5 am.

Further investigation tied the gang to more than 60 cases in the districts of Chaoyang, Tongzhou and Daxing since 2007. While officers suspect the gang of involvement in the 60 cases, investigators have, so far, only built a case against the gang for 47 of them. The investigation is continuing.

Meanwhile, officers are urging small- and medium-sized enterprises to strengthen their internal security and not keep large quantities of cash on the premises. Business owners and managers are also advised to call the police immediately if they are the victims of a robbery.