Special measures might be needed to curb a rising tendency in Western nations for smokers to roll their own cigarettes -- either to cut the cost of smoking or from a belief that loose tobacco is less hazardous than factory- made cigarettes, a New Zealand expert warned Wednesday.

Evidence showed that roll-your-own (RYO) cigarettes were at least as harmful as the factory-rolled type, although many RYO smokers falsely believed they were more "natural" and less dangerous, said University of Otago Wellington Professor of Public Health Richard Edwards

In Canada, the United States, Australia, the United Kingdom and New Zealand, between 21 percent and 40 percent of RYO smokers reported that they thought they were healthier.

However, in New Zealand, the concentration of additives in loose tobacco was about 18 percent compared with 0.5 percent for factory-made cigarettes, Edwards said in a statement.

RYO consumption had been rising greatly in some countries, such as the UK, where their use among smokers older than 16 rose from 2 percent to 23 percent among women and from 18 percent to 39 percent among men between 1990 and 2010.

Edwards said the high use among youth "further suggests that they may have a specific role in facilitating initiation of smoking."

Evidence also indicate a high rate of RYO cigarettes in disadvantaged groups in many countries with higher usage among black South Africans, Maori in New Zealand and smokers of lower socioeconomic status in Australia, the UK, the US and Canada.

Edwards said measures to reduce smoking among RYO smokers "need to be formulated with an awareness of the extent of use of RYO cigarettes" or the sale of loose tobacco could be banned altogether.