LONDON (Reuters) - Quick treatment of minor strokes can greatly reduce the chance of a major stroke later, but most patients are not getting care in time, according to two studies published on Tuesday.

The researchers showed that immediately treating small strokes cut the risk of a disabling or deadly stroke in the next 30 days by about 80 percent, said Peter Rothwell, a neurologist at the University of Oxford, who led one of the studies.

Most follow-on strokes happen within 30 days of a smaller one, but most patients do not get treatment for weeks, he said.

"These mini-strokes are essentially warning events," he said in a telephone interview.

Strokes, which occur when blood flow to the brain is blocked, can kill brain tissue and are one of the worldwide leading causes of death and permanent disability. Treatments include blood thinning drugs and attempts to lower cholesterol.

The researchers were looking at so-called ischaemic strokes, caused by a blood clot, and not the more unusual haemorrhagic strokes, caused by bleeding in the brain.

In the study, published in The Lancet medical journal, researchers found the risk of a major stroke within the first month following a minor one fell to about 2 percent from 10 percent for patients who received treatment almost immediately.

Rothwell estimated that early treatment could help prevent 100,000 strokes each year in Britain alone.

"The vast majority of patients in Britain have not been getting treatment for the first few weeks," he said. "This is similar in the United States and most of Europe."

The second study, published separately in The Lancet Neurology by French researcher Pierre Amarenco and colleagues, also found that early aggressive treatment brought similar results in cutting the chance of a major stroke.