The UK's data protection watchdog fears racial background and religious beliefs could be included in plans to introduce an ID card.

The so-called entitlement cards are expected to contain personal details such as those found on passports and driving licences.

How do you stop it being a requirement for sensitive data, racial background, religion or political views being held by the state? Richard Thomas

The government has outlined various options for the amount of information to be on the cards and what they would be used for - such as claiming services and benefits.

But the Information Commissioner, Richard Thomas, said the proposals were so widely drawn he had "serious concerns" over whether the cards would comply with privacy and data protection laws.

Although he realised that individuals sometimes needed a simple way of proving their identity, he identified several problems with the plans as they were.

Misuse fears

The cards could be a "target" for fraudsters and there would probably be "function creep", where they would end up being demanded in situations where they were not really needed, he said.

There was a risk of ever-more information being added, and ever-greater state monitoring of individuals' activities.

Burnham: Benefits outweigh the negatives

A massive central database of information would be needed to run the scheme, and the task of keeping this accurate and up-to-date would be enormous, he said.

"Identity cards may be okay, but why do you draw the line? How do you stop it being a requirement to hold a card in public?" said Mr Thomas.

Safeguards needed

"How do you stop it being a requirement, for example, of sensitive data ... racial background or religion or political views - all that being held by the state?

"I do have anxieties about a monolithic state system having so much information on every single citizen in this country," Mr Thomas told BBC Radio 4's Today programme.

Home Secretary David Blunkett has made it "very clear" that the fight against crime and against terrorism "is not the prime motivator for this scheme", he said.

Mr Thomas said: "We want the government to be much more focused about what the purpose is, then we can start talking about what safeguards do we need.

"The police, by and large, say they know who the villains are - identity is not a major problem as far as the police is concerned."

Mr Thomas said he knew of no other identity card scheme across the world that was "as ambitious" as the one being proposed in this country."

He also called for:

• An independent body to administer the scheme
  
• Strict limits on the amount of information held on the card
  
• Effective sanctions against misuse
  
• Reliable identity validation, possibly with a form of biometric identifier, and
  
• Strengthened data protection supervision and inspection powers.

He said it could be possible for the government to rewrite its proposals so they met all his objections - "but the task would be a challenging one".

But Labour MP Andy Burnham said he believed the "simple benefits" of an ID card scheme "outweighed some of the negatives".

"I have come to the conclusion that an identity card would be in the interest of the majority of people who carry their identity anyway," he told Today.

'Public trust'

Meanwhile, officials in Whitehall were reported to be looking for ways to combat public fears of a "Big Brother" approach by the government in its collection of information on individuals.

According to the Guardian, officials on the inter-departmental group looking at data privacy and freedom of information "public trust" was "a particularly difficult issue in this context".

Papers leaked to the paper also reportedly disclosed that Downing Street had thwarted attempts by 100 Tory MPs to discover what information it was keeping on them.

The Home Office said it would study Mr Thomas's comments carefully, as well as the views of 2000 other people who had responded during the consultation period.

Mr Blunkett favours the scheme, but other ministers have already hinted the proposals could be abandoned.