QUITO (AFP) - Ecuador lashed out at Swedish prosecutors on Friday for their delay in agreeing to question WikiLeaks founder Julian Assange at its embassy in London in their case against him on rape allegations.

"If they had accepted Ecuador's offer to question him (at the embassy) 1,000 days ago, it would have saved us all a lot of money and trouble," Foreign Minister Ricardo Patino wrote on Twitter. "On Monday Assange will mark 1,000 days inside our embassy in London. From the first day we have offered to let (prosecutors) question him and they didn't do it.

"The reason for taking Assange's statement now, after 1,000 days, is the statute of limitations. And if the statute of limitations were five years?"

Mr Assange took refuge in the Ecuadoran embassy in 2012 to avoid extradition to Sweden to face the charges, which he denies. He has been there ever since, saying he fears Sweden will extradite him to the United States, where an investigation is ongoing into WikiLeaks' release of 500,000 classified military files on the wars in Iraq and Afghanistan and 250,000 diplomatic cables.

The mass leak in 2010 deeply embarrassed Washington.

The lead prosecutor in the Swedish case, Ms Marianne Ny, said she had reluctantly agreed to question Mr Assange at the Ecuadoran embassy because the statute of limitations on some of the charges will expire in August.

Ms Ny's office said in a statement she had always believed that interrogating Mr Assange at the Ecuadorean embassy would "lower the quality of the interview, and that he would need to be present in Sweden in any case should there be a trial".

"This assessment remains unchanged," she said, but added "now that time is of the essence, I have viewed it therefore necessary to accept such deficiencies... and likewise take the risk the interview does not move the case forward, particularly as there are no other measures on offer without Assange being present in Sweden".

Ms Ny has also asked to take a DNA sample from Assange.

One of Assange's lawyers welcomed the prosecutors' proposal, saying the interview would be a first step in clearing his client who took refuge in the Ecuadorean embassy in 2012 to avoid extradition to Sweden and has been there ever since.

"He will accept" to be questioned in London, lawyer Per Samuelsson told AFP, adding that Assange was "happy" about the development.

"We are cooperating with the investigation," he said.

Britain's Foreign Office pledged its help, saying: "As we have made clear previously, we stand ready to assist the Swedish prosecutor, as required."

However, WikiLeaks said the handling of the case had left a "black stain" on Sweden's human rights record.

Up to now, Swedish prosecutors have refused to go to London to question the 43-year-old Australian former hacker over the allegations.

A lawyer for one of the women urged Swedish authorities to question Mr Assange as soon as possible. "For my client, possible charges must come before August," her lawyer Claes Borgstrom told AFP, who noted the statute of limitations in Sweden is five years for sexual assault and 10 years for rape.

Ms Elizabeth Fritz, a lawyer for the other woman, told AFP in an email: "Assange did not make himself available to be interviewed in Sweden... That's why it is necessary to change the location of the interview."

In 2012, Ms Assange took refuge in Ecuador's embassy in London, where British police officers stand guard around the clock, at a cost so far to British taxpayers of almost £10.4 million, according to WikiLeaks.

The anti-secrecy group slammed Swedish prosecutors for waiting so long to make the offer.

"It is outrageous that the Swedish authorities have waited four and a half years to come to this decision," WikiLeaks spokesman Kristinn Hrafnsson told AFP.

"This entire saga is a black stain on Sweden's human rights record. It is time the authorities face it and drop the case entirely," he said.

One of Mr Assange's main financial supporters, Australian-born campaigning journalist John Pilger, described the Swedish prosecutor's offer as "demonstrably cynical".

"In finally agreeing to come to London to interview Julian Assange... she has waited until just before Sweden's statute of limitations nullifies her threadbare case against him," Mr Pilger said.

"She has wasted 41/2 years of Assange's life - against whom she has never had a shred of evidence to charge him with any crime.

"Her behaviour is scandalous," he added said.