Nearly 300,000 Junior Isas were opened last year as the popularity of the children's savings accounts gathered momentum.

Six million children were eligible to open Junior Isas, or Jisas, when they were launched in autumn 2011 as part of Government efforts to strengthen the savings culture.

Figures released by HM Revenue and Customs (HMRC) showed 295,000 of the tax-free accounts were opened in 2012-13, the first full tax year of the scheme, of which the vast majority were cash savings accounts rather than stocks and shares.

In the previous financial year, 71,000 accounts were opened in the five months after launch.

The average investment in the last financial year was £1327, edging down slightly from £1623 the previous year.

Jisas are the successor children's savings accounts to Child Trust Funds (CTFs), introduced under the previous government.

A parent whose child holds a CTF cannot transfer the account into a Jisa.

This has caused ­frustration among many families trying to build up their child's nest egg as competition among providers to offer attractive deals tends to be concentrated around newer Jisas.

The Government launched a consultation in May into opening up Jisas to those whose money is trapped in CTFs. The consultation document said the Coalition's preferred option is to leave parents to decide whether they want to transfer funds rather than merging the accounts.