Police were last night investigating claims that Robert Murat hired a car two days before he was questioned as the "main suspect" in the abduction of Madeleine McCann.

It was claimed that Mr Murat telephoned a Praia da Luz hire company just after noon on Saturday and ordered a vehicle "in a hurry". Mr Murat has revealed he knew he was being followed by undercover officers at that time.

Mario Rocio, an assistant at Auto Rent III, claimed he was acting suspiciously. She said: "There was something in his voice. I thought he needed a car in a hurry."

Mr Murat said he wanted to hire a car because his own was being used to help in searches for "the missing little girl". The Hyundai, which was still in his drive when he was arrested on Monday, was searched along with a green Volkswagen van.

Claims were made yesterday in a Portuguese newspaper that home-made video tapes of a "disturbing sexual nature" were found at Mr Murat's villa.

A spokesman for Mr Murat said the graphic allegations were "disappointing". Tuck Price, a friend of the British expatriate, denied the claims and said that police were "clutching at straws".

Mr Murat's elderly mother, Jennifer, was interviewed by police yesterday to stand up her son's alibi. Mr Murat, 33, said he was with her on the night Madeleine disappeared a fortnight ago.