Special courtrooms in the Seychelles and Mauritius and purpose-built "pirate prisons" are among measures to be outlined this week as world leaders gather to plan a crackdown on Somali pirates.

David Cameron and other world leaders are expected to announce the moves at a meeting in London on Thursday. The aim of the gathering will be to hammer out a plan to improve stability in Somalia, which for more than 20 years has been lawless and beset by pirate gangs, rival clan militias and Islamist terrorists.

Drastic action is needed: more than 4,000 Somali pirates have been captured and released since 1999, nearly five times the number that have been successfully prosecuted. Not a single convicted pirate has completed their sentence.

Britain will work alongside UN officials looking at a range of measures, including transferring pirates to the Seychelles and Mauritius for trial under international law, and pouring money into internationally managed prisons in Puntland, to the north-east, and Somaliland, in the north. Delegates will also consider bringing captured pirates to the UK for prosecution.

Peter Cook, founder of the Security Association for the Maritime Industry, said: "Having internationally certified prisons in Somaliland and Puntland ensures that pirates stay within Somalia and is ultimately more constructive than someone disappearing into a Western country. It will build rather than destroy confidence in the regions, and ensures that there is a rule of law that sets a precedent. Eventually it could work its way down the coast."

Seafarers and shipping operators are increasingly angry that more has not been done to curb piracy in the Indian Ocean. Attacks rose to a record 237 in 2011, with ransoms worth £100m paid to release 31 hijacked vessels, according to a One Earth Future Foundation report released last week.

The UK remains one of the few Western nations not to have prosecuted a single pirate in the past three years, despite the taking of British hostages such as Paul and Rachel Chandler, who were kidnapped by Somalis for 13 months, and Judith Tebbutt, who was kidnapped from a Kenyan beach resort last September after her husband was shot. She has not been seen since.

Critics say the British approach is in stark contrast to that of the US, which has deployed special forces and drones for assassination missions. "No other country greets piracy with such a culture of silence," a senior security source said last night. "The UK's current deterrent amounts to nothing. Getting captured means, in most cases, losing your weapons and being taken back to Somalia and left on a beach."

But protests are being planned by campaigners who accuse the London Somalia Conference of having little to do with piracy or terrorism and instead being an attempt by Britain to secure its economic interests in the oil-rich and strategically important Horn of Africa.