Lord Coe has defended drug testing systems in world athletics, insisting it is time to "come out fighting" to protect the reputation of the sport in the face of doping allegations he described as a "declaration of war".

Fresh allegations have recently been made claiming that the International Association of Athletics Federations (IAAF) had failed to act on suspicious blood tests involving hundreds of athletes over a 10-year period.

In his first comments about the allegations, Lord Coe, an IAAF vice-president, said: "It is a declaration of war on my sport. I take pretty grave exception to that.

"This, for me, is a fairly seminal moment. There is nothing in our history of competence and integrity in drug-testing that warrants this kind of attack. We should not be cowering. We should come out fighting."

Just weeks before the world championships in Beijing, the sport was thrown into turmoil after German broadcaster ARD and The Sunday Times alleged blood doping was rampant, citing test results from an IAAF database that were leaked by a whistle-blower.

"Nobody should underestimate the anger at the way our sport has been portrayed," said Lord Coe, who is a candidate for IAAF president in elections later this month.

"The fightback has to start here. We cannot be portrayed as a sport that is in any way dragging our heels."

The media reports examined the results of 12,000 blood tests involving 5,000 athletes from 2001 to 2012, and concluded that 800 were suspicious.

The reports said that 146 medals - including 55 golds - in disciplines ranging from the 800 metres to the marathon at the Olympics and world championships were won by athletes who have recorded suspicious tests.

"The use of that database, however it got into their possession, displayed either breath-taking ignorance or a level of malevolence around a set of readings you simply cannot extrapolate beyond," Lord Coe said.

"The idea that my sport sat there either covering up wrongdoing or just being incompetent could not be wider of the mark."

Lord Coe, the middle-distance great who organised the 2012 London Olympics, was speaking as the IAAF issued a lengthy statement defending its procedures and calling the media allegations "sensationalist and confusing".

The ARD and Sunday Times reports were based on analysis of the leaked test results by Australian anti-doping scientists Robin Parisotto and Michael Ashenden.

Lord Coe questioned their credentials, saying: "These so-called experts - give me a break."

The IAAF has a commission of three independent experts who have tested and checked thousands of blood samples, Lord Coe said. "I know who I would believe," he added.

The IAAF said the database was used for building up a record of blood profiles to use for target testing. Most of the samples were taken before the introduction of the biological passport programme and cannot be used as proof of doping.

"The use of this stuff, the sensationalising, this is absolutely an attempt to destroy the reputation of the athletes and our sport," Lord Coe said.

"Nobody is remotely suggesting that news organisations don't have the right to question and challenge and kick the tyres. But this selective use of this so-called information is just wrong."

Lord Coe said the IAAF has been at the forefront of blood screening and out-of-competition testing for years.

"We will not bend a knee to any other sport in the way we've led the way on this," he said, noting that since 2011, the IAAF has pursued 63 cases based on the biological passport programme, with 39 athletes sanctioned so far.

Lord Coe is competing against pole vault great Sergei Bubka to succeed Lamine Diack as IAAF president. The election will be held in Beijing on August 19, ahead of the world championships from August 22-30.