By Eleanor Bradford BBC Scotland health correspondent

The 500 haemophiliacs in Scotland who contracted hepatitis C through contaminated blood products have been through a great deal.

They already have a blood disorder which, if left untreated, causes crippling joint damage.

But the drug they were given to improve their quality of life infected them with even more serious conditions - hepatitis C and HIV.

The effects of full-blown Aids are well known. Hepatitis C causes chronic liver damage in 80% of patients.

Limited payouts

For years they have been battling for compensation.

Those who contracted HIV have received limited payouts.

However, those who have hepatitis C have been refused on the grounds that little was known about these viruses at the time they were treated, and therefore infection was "accidental".

Scottish Health Minister Malcolm Chisholm has promised to look into other forms of help, but 135 patients have already died.

Malcolm Chisholm is writing to NHS chiefs

Many of those who are still alive have lost friends, family, livelihoods and even their homes.

A small number were treated with highly contaminated blood products from America - and they have a good chance of winning damages against the manufacturers.

To prove their case they need the batch numbers from their medical records.

But every patient has been told by at least one hospital that these are "missing" or "unavailable".

Under American law, the case has to be brought within 12 months, and some patients have already wasted four months trying to obtain their notes.

Blood products

The BBC has been that Mr Chisholm will be writing to all Scottish hospital chief executives, urging them to comply with the law and release the information.

However, the extent of the problem is unusual and begs the question: "What is the NHS so keen to hide?"

Some haemophiliacs argue that they were being prescribed untreated blood products after doctors should have known they were dangerous.

That is an allegation strenuously denied by the NHS - but it needs to be more open and helpful if patients are to believe it.