A range of instutions from Hargreaves Lansdown to Fidelity FundsNetwork are already offering the accounts.

All children under 18 who do not have a Child Trust Fund will be eligible for a Junior Isa and the number is set to increase by 800,000 each year.

The limit for the account will be £3,600, split between cash and stocks and shares.

Mark Hoban, financial secretary for the Treasury, said: “The launch of the Junior Isa is a clear demonstration of the Government’s commitment to encourage saving for children. “Junior Isas will be open to all parents, regardless of income. This, together with changes made to Child Trust Funds, mean that parents can save up to £3,600 per year for their child.”

M&G, Hargreaves Lansdown, Fidelity FundsNetwork and Nationwide have all launched their Junior Isas already while others will be launching into 2012.

David White, head of Fidelity FundsNetwork, said: “We are keen to support advisers who want to offer this as an additional tax wrapper for their clients.

“We have seen hundreds of IFAs pre-registering with FundsNetwork for information packs. We believe the Junior Isa is set to become another important part of an adviser’s overall approach to tax planning for their clients.”

Ben Yearsley, investment manager at Hargreaves Lansdown, said: “Those investing for more than five years should consider investing with top quality fund managers in a stock market Junior Isa as this will provide the best potential for returns over the long term”