BRITISH athlete Diane Modahl has claimed that there had been

''material changes'' to the B sample of her drug test and again pledged

to prove her innocence.

The International Amateur Athletic Federation -- world governing body

of the sport -- has announced that the second urine sample taken from

the banned runner at a meeting in Lisbon in June had proved positive.

The 28-year-old now has been suspended pending a hearing of the

British Athletic Federation within the next 30 days. But, last night,

Modahl challenged the IAAF's drug-testing procedures and said she

intended to produce evidence at the hearing which will show ''once and

for all that no doping offence has been committed.''

In a prepared statement, issued through her solicitors, Modahl said:

''The confirmation of the A test result and today's announcement by the

IAAF have not addressed the underlying criteria which govern doping

offences under IAAF rules.

''It has not been established by the IAAF that there has been an

'administration of testosterone or the use of any other manipulation

having the result of increasing the ratio in the urine of

testosterone/epitestosterone. The laboratory findings are not proof that

either of these two events occurred.

''Additionally there are many other relevant factors still requiring

careful consideration. It was, for example, apparent to those witnessing

the B test that there have been material changes to the characteristics

of the sample between 18 June (when the sample was obtained) and

yesterday (when it was tested again).

''This raises serious questions as to compliance with IAAF guidelines

in relation to the storage and treatment of samples pending analysis.

The IAAF has yet to give an explanation for those changes.''

Modahl added that she would be exercising her right to call a full

hearing of the BAF and will not be making any further statement until

that hearing has been concluded.

IAAF spokesman Chris Winner agreed with Modahl's claim that athletics'

governing body had not established that there had been administration of

testosterone, but pointed out: ''That is a minor point.''

However, he denied any suggestion that her B sample had been tampered

with. ''This suggestion we don't for an instant countenance,'' he said.

''What I do know is that the presiding doctor noted minor changes to the

composition of the urine. They could be ascribed to the passage of time.

''One thing that didn't change was the presence of testosterone at the

same level -- 42 to one.''

The normal level is 1-1 and a ratio of 6-1 or more is considered

positive, resulting in a four-year ban.

''The suggestion is that somebody knows the reason for this astounding

ratio, but is not willing to disclose it,'' added Winner, who took the

unprecedented step of revealing the ratio ''to stop the rumours.

If somebody knows how an athlete comes to have such a high level of

testosterone in their body, then can they please let us know. It's a

level that no-one has ever seen before. As far as we are concerned, she

is guilty.''

Meanwhile, Winner has said that the British team should be pulled out

of next week's World Cup in London, stating that the Crystal Palace

meeting will be overshadowed by the Modahl situation. ''It is their

moral obligation to pull the team out,'' he said.

''The World Cup is not just about the British women. If Diane Modahl

is to be redeemed and it can be done before the World Cup, then fine.

But should Britain compete and Sally Gunnell break a world record, then

it could be expunged.