Disgraced MP Fiona Onasanya will not have her three-month jail sentenced extended after the Solicitor General decided not to refer her case to the Court of Appeal.

The Peterborough MP was convicted at the Old Bailey of perverting the course of justice after lying to police to avoid a speeding charge. She was jailed in January but is continuing in her role despite calls for her to stand down.

In the days after her conviction, the Attorney General's office received a complaint insisting the three-month sentence was "unduly lenient".

The office had 28 days to consider the case, but on Monday, a spokeswoman for the Attorney General’s Office said: "After careful consideration the Solicitor General has concluded that he could not refer this case to the Court of Appeal.

"A referral under the Unduly Lenient Sentence scheme to the Court of Appeal can only be made if a sentence is not just lenient but unduly so, such that the sentencing judge made a gross error or imposed a sentence outside the range of sentences reasonably available in the circumstances of the offence.

"The threshold is a high one, and the test was not met in this case."

If the sentence had been found to be unduly lenient, the case would have been referred to the Court of Appeal which would decide whether or not to increase it.