Image caption The drug will be given to patients suffering from serious medical conditions

The US state of New York is planning to relax its marijuana laws to allow limited use by seriously ill patients, reports say.

Democratic Governor Andrew Cuomo - long opposed to the legalisation of medical marijuana - is to make the announcement this week, the New York Times says.

Twenty US states have already gone down the same road.

On Wednesday, Colorado became the first US state to allow shops to sell cannabis for recreational purposes.

Washington state is expected to allow the sale of marijuana later in 2014.

The drug is still illegal under federal law.

New York's new policy is expected to be far stricter than in California or Colorado, which had already loosened rules around the use of medical marijuana.

In California, people suffering from mild medical complaints can obtain prescriptions for the drug.

But in New York, the drug will be made available in only 20 hospitals across the state for people with cancer, glaucoma or other serious diseases that meet standards to be set by the state department of health.

Mr Cuomo is to formally announce his plans in his state of the state speech on Wednesday.

He is expected to make the change through administrative rather than legislative action, according to Associated Press.