The letter, from the All Party Parliamentary Group for Democracy in Bahrain, cites "the most atrocious human rights violations" as reason the race should be called off and has been signed by 20 MPs.
The chair of the APPG, Labour MP for Hammersmith and Shadow Justice Minister Andy Slaughter, believes the race "is likely to attract as much negative publicity as last year".
In the letter, dated on Monday and seen by the media, Slaughter adds: "Since April 2012, many more people, including children, have lost their lives and the whole country exists in fear and intimidation.
"Leading human rights activists, such as Nabeel Rajab, have been imprisoned for merely speaking out against a dictatorship of a ruling family.
"Children, medical staff, men and women languish in jail on the whims of the Al Khalifa (ruling royal family) when no crime has been committed and child deaths are the norm.
"Last year's championship was held under conditions of martial law. Three hundred protesters were arrested, some spending months in jail.
"Salah Abbas Habib was killed during the weekend of the race. He was shot by the security forces and his body showed marks of torture.
"I think most democratic-minded people would be appalled if you allowed the Bahrain leg of the Formula One championship to go ahead amidst the most atrocious human rights violations."
Slaughter, along with nine other MPs, also put his name to the early day motion that was tabled yesterday.
That read: "That this House calls for a boycott of the forthcoming Bahrain Formula One Grand Prix on moral grounds, given the continued human rights abuses committed by the Bahrain government against its citizens as detailed by Amnesty International, Human Rights Watch and other organisations; believes that if it went ahead, the race would be used by the Bahrain government to present a false image to the world; is concerned that the human rights situation has not improved since the 2012 race; notes that the Bahrain government has failed to implement reforms it pledged to enact in 2011; and further notes that the Bahrain government is keeping prominent human rights defenders and political activists behind bars and continues to suppress, injure and kill peaceful protestors with excessive tear gas and birdshot."
Ecclestone was unmoved last year by a similar call from MPs, when even Labour leader Ed Miliband voiced his opposition to the race taking place, and it is certain his feelings will be the same now.
The 82-year-old yesterday did express empathy with the protest movement, and claimed he would be willing to talk to leaders from both sides if he felt it would help, as he did a year ago.
It was two years ago the race was cancelled following a bloody uprising, resulting in the deaths of a number of protesters.
Last year the grand prix went ahead against a taught backdrop as daily protests saw demonstrators armed with Molotov cocktails take on police retaliating with tear gas, sound bombs and birdshot.
A year on, with the race looming on the horizon this Sunday, the tension is nowhere near as high as last April, but the political struggle goes on.
Protesters have been further outraged by a move from the government, endorsed on Sunday, that will result in them being jailed for up to five years for insulting King Hamad.
Opposition groups often chant 'Down, down Hamad', but such cries in the future will now see them thrown in prison, a move that has angered Amnesty International.
Hassiba Hadj Sahraoui, deputy Middle East and North Africa programme director at Amnesty International, said: "Increasing the punishment for criticism of Bahrain's king is a further attempt to muzzle activists ahead of the upcoming grand prix.
"The authorities' reliance on a vaguely worded criminal 'offence' to avoid scrutiny of their record says a lot about their own failures and lack of commitment to reform."