The Foreign Office initially advised a Muslim peer not to go to Sudan to try to negotiate teacher Gillian Gibbons's release, he has told the BBC.
Lord Ahmed lobbied for Mrs Gibbons's release
Lord Ahmed made his own arrangements after he was told to wait for the foreign secretary to make a decision.
The Labour peer and Conservative peer Baroness Warsi lobbied the Sudanese president for Mrs Gibbons's release.
She spent eight days in custody for insulting Islam before being granted a presidential pardon.
The case began when Mrs Gibbons, 54, allowed children in her class to name a teddy bear Muhammad.
Lord Ahmed told BBC News 24's Straight Talk with Andrew Neil that, when he first heard of the story, he contacted someone he knew who worked for the Sudanese government.
Once the case went to court the peer was told that, if Mrs Gibbons was convicted, they would have to try to secure a presidential pardon - and that was when Lord Ahmed contacted the Foreign Office.
He told the programme: "I got a telephone call at 9 o'clock on Thursday night and I called the Foreign Office immediately and the response unit, actually, they advised me not to go."
He insisted on speaking to someone else, but said it took "a very long time" for them to make a decision - then he was told Foreign Secretary David Miliband would make the final decision the next day.
In the end, he said, he pressed ahead and made all his own arrangements because he had to book the flight and get the visa sorted out.
'Not about credit'
He said the Foreign Office stressed he was there as "an individual Parliamentarian", not to represent the government and advised him that they did not recommend people travel to Khartoum.
Meanwhile the Conservatives had contacted the Foreign Office as well, about sending Baroness Warsi to Sudan.
Lord Ahmed said they were able to speak to the Sudanese government, whereas the British ambassador and government officials would not have been granted access because of "problems between the Foreign Office and the Sudanese government".
But, asked whether the Foreign Office had tried to "muscle in" and take some of the credit, he replied: "Well you know, because the ambassador was involved, let's be honest, I think, it's not about credit.
"I think that it was a great success; Gillian was healthy, she was fit, she was in good form, we all together, all of us, worked together for her release."
Mrs Gibbons is now back in Liverpool after President Omar al-Bashir pardoned her. She has thanked both Lord Ahmed and Baroness Warsi for their efforts in Sudan.
Watch the full interview with Lord Ahmed on BBC News 24's Straight Talk with Andrew Neil on Saturday, 8 December at 0430 and 2230 and Sunday, 9 December at 0130 and 2230.