A single judge bench of Allahabad High Court held as follows,

It is true that filing of first information report (F.I.R.) is not a condition precedent to exercise the power under Section 438(1) Cr.P.C., as held in Gurbaksh Singh Sibbia Vs. State of Punjab,(1980) 2 SCC 565, but at the same time it is also to be kept in mind, as held in the aforesaid case by the Hon’ble Apex Court, that“when a person apprehends arrest and approaches a court for anticipatory bail, his apprehension (of arrest), has to be based onconcrete facts (and not vague or general allegations) relatable to a specific offence or particular offences. Applications for anticipatory bail should contain clear and essential facts relating to the offence, and why the applicant reasonably apprehends his or her arrest, as well as his version of the facts. These are important for the court which is considering the application, the extent and reasonableness of the threat or apprehension, its gravity or seriousness and the appropriateness of any condition that may have to be imposed. It is not a necessary condition that an application should be moved only after an FIR is filed; it can be moved earlier,so long as the facts are clear and there is reasonable basis for apprehending arrest.“

Then, What is ‘Reason to Believe‘?

The Hon’ble Apex Court in Adri Dharan Das Vs. State of West Bengal, (2005) 4 SCC 303 has emphasized over this requirement and held as under.
“Section 438 is a procedural provision which is concerned with the personal liberty of an individual who is entitled to plead innocence, since he is not on the date of application for exercise of power under Section 438 CrPC convicted for the offence in respect of which he seeks bail. The applicant must show that he has “reason to believe” that he may be arrested in a non-bailable offence. Use of the expression “reason to believe” shows that the belief that the applicant may be arrested must be founded on reasonable grounds. A belief can be said to be founded on reasonable grounds only if there is something tangible to go by on the basis of which it can be said that the applicant’s apprehension that he may be arrested is genuine. Mere “fear” is not “belief” for which reason it is not enough for the applicant to show that has some sort of vague apprehension that some one is going to make an accusation against him in pursuance of which he may be arrested. Grounds on which the belief on the applicant is based that he may be arrested in non-bailable offence must be capable of being examined. If an application is made to the High Court or the Court of Session, it is for the court concerned to decide whether a case has been made out of for granting of the relief sought. (Para 16)”
The aforesaid theory makes the legal position explicit that Section 438 (1) of Cr.P.C. applies not only at post FIR stage, but it does not require that the offence must have been registered. It is contemplated by this section that if a person is going to apply for anticipatory bail, he must have a reasonable belief that he may be arrested on accusation of having committed a non-bailable offence.