International Development Secretary Hilary Benn wrote to government colleagues arguing that the weapons were "essentially equivalent to land mines" and caused thousands of unnecessary deaths.
His comments clash with the British government's position that cluster munitions play a "legitimate" role in modern warfare and that it would be "unfair" on British troops not to use them when enemies were doing so.
Benn said Britain should push for a ban on cluster bombs at a ban at a major international arms convention in New York next week.
The letter was sent recently to Foreign Secretary Margaret Beckett and Defence Secretary Des Browne.
Benn wrote: "The high failure rate of many cluster munitions, and the failure of many militaries around the world to use these munitions in a targeted way means that cluster munitions have a very serious humanitarian impact, pushing at the boundaries of international humanitarian law.
"It is difficult then to see how we can hold so prominent a position against land mines, yet somehow continue to advocate that use of cluster munitions is acceptable."
Britain is a signatory to the 1997 Ottawa Treaty banning the use of all anti-personnel land mines.
The United States, China, Russia, India, Iraq and Israel are among 40 countries which have not signed the mine ban treaty.
Benn said British representatives should go into the New York arms convention "advocating for a process that will lead to an effective ban of 'dumb' cluster munitions".
The charity Handicap International said in a report Friday that there had been 10,861 confirmed cases where people had been killed or maimed by cluster bombs worldwide over the past 30 years.
It said 98 percent of the victims were civilians, adding that the total number of cases could be far higher -- up to 100,000 -- due to the difficulty of collecting data in conflict zones.
Last week, Benn became the fourth candidate to launch a bid for the deputy leadership of the governing centre-left Labour Party once Prime Minister Tony Blair and his deputy John Prescott step down, set to happen by September 2007.
If successful, he would therefore become deputy prime minister.
The Sunday Times weekly broadsheet said the letter could be interpreted as an attempt to woo Labour left wingers.

Copyright AFP (Agence France-Presse), 2006