Plans to merge four Midlands police forces and create a giant “superforce” are to be resurrected by the Home Secretary.

Jacqui Smith (Lab Redditch) will tell forces to consider joining together. It could mean the abolition of the West Midlands, Warwickshire, Staffordshire and West Mercia forces to create a single constabulary serving five million people.

Similar proposals were abandoned two years ago following opposition from West Mercia. But the Government is expected to make the scheme strictly voluntary this time, with promises of extra funding for forces which agree to unite.

HM Inspectorate of Constabulary has warned that smaller forces such as Warwickshire and West Mercia do not have the resources to deal with issues such as terrorism and cross-border crime. Fresh merger plans will be outlined in a Green Paper to be published by Ms Smith next week.

Worcestershire MP Peter Luff (Con Mid Worcestershire) said he would be opposed to any merger between West Midlands Police and West Mercia. He said: “I would resist that very strongly, because they are very different styles of policing and I would be concerned about the allocation of resources.”

One of the obstacles to a merger is the difficulty in creating a single police precept, which is added on to council tax bills, for the entire region. Council taxpayers in the area covered by West Midlands Police are paying a precept this year of £94.67, while the West Mercia precept is £165.45.

However, if the forces merged then there would have to be a single precept for the entire area – meaning households in the West Mercia force area received higher council tax bills.

The Green Paper will also include proposals to make it easier for police to stop and search people. Ms Smith wants to abolish the requirement that officers complete a 30cm-long form every time they stop someone.

The forms will be replaced by new radio technology, allowing officers to verbally transmit the details of each stop back to the station. The person stopped would be given a card recording the incident, with a number to call.

But this proposal, which has already been tested by West Midlands Police, is also likely to be controversial after figures earlier this week showed that black people are more than five times as likely to be stopped by police than whites.

The Ministry of Justice revealed that West Midlands Police stopped 27,125 people in 2006-7. They included 14,927 whites, 5,249 black people and 6,058 Asians. It means black people were stopped far more often than whites, taking into account the make up of the general population.

Out of every 1,000 white people in the West Midlands, eight were stopped and searched by police. But out of every 1,000 black people, 46 were stopped and searched. Police stopped Asian people 19 times for every 1,000 Asian people in the population.

Other changes include giving the public a new chance to vote directly for members of the bodies which oversee police forces.

Voters would have a direct influence on police authorities, which are currently made up of local councillors and other members such as magistrates.

Hazel Blears, the Local Government Secretary, revealed this week that the Government will also give elected mayors a role overseeing police services.