SALES of popular investment funds that promise a regular income have hit a record high amid fears that many savers are putting their cash at more risk than they realise.Private investors ploughed GBP500 million more into UK equity income funds in April than they withdrew, the biggest monthly inflow since records began in 1992.The surge contributed to total fund sales of almost GBP3 billion over the month, the highest since April 2011, as investors used up both their old and new Isa allowances."The strong performance of stock markets in 2013 combined with low returns on cash has helped drive up demand for investments," said Adrian Lowcock, senior investment manager at Hargreaves Lansdown."UK equity income funds have been popular with investors as they have grown more cautious in recent months following the recent strong performance of equity markets."The appeal of UK equity income funds lies in their ability to deliver both a regular income and capital growth. That blend makes them a perennial favourite with risk averse investors and retirees looking for a regular income.But some experts are uneasy about the sheer volume of money invested in UK equity income funds in recent months.William Hunter, director of Hunter Wealth Management in Edinburgh, believes the funds are attracting large numbers of savers who are frustrated by the lack of returns on cash and want more regular income but who are unaware of the risk to their capital."Cautious savers looking for higher income and switching from cash to investing in this sector may not be prepared for big shocks in the value of their capital if they pick the wrong funds and there is a correction in the market," said Hunter.The danger lies largely in the size of the sector, which houses 366 funds with varying remits and risk profiles."With so many funds in there it's not difficult to pick the wrong one," said Hunter. "There is a massive range in performance and quality in the sector."He used the comparison of the Elite Charteris premium income fund, down 1.3 over the last year, with the Axa Framlington Monthly income fund, which is up 23.8 per cent over the same period."Equity income funds hold big household names such as Royal Dutch Shell, Glaxo, and BP," said Hunter. "But with a lot of these companies achieving growth globally, the strong pound may make it difficult for them to convert that to share price growth and high dividend pay-outs."There are also fears that some funds have become too risky for the UK equity income umbrella, with falling dividend yields forcing some to increase their exposure to more volatile assets in a bid to produce a decent income.The Investment Management Association (IMA) was recently forced to eject the GBP13bn Invesco Perpetual High Income fund from the sector after the fund failed to meet its rolling three- year yield requirements.Under the IMA's UK equity income rules, funds must produce income at least 10 per cent higher than the FTSE All Share index over rolling three-year periods. The High Income fund, run until recently by Neil Woodford, is now in the growth- focused UK All Companies sector. It is likely to be joined there by several other popular UK equity income funds over the coming months.