Algerian Visa
Requirements
All visitors to Algeria will require an Algerian visa, except for nationals from the following countries, who can enter the country without making a visa application:
Libyan Arab Jamahiriya, Malaysia, Maldives, Mali, Mauritania, Morocco, Democratic Republic Sahraoui, Seychelles, Syrian Arab Republic, Tunisia, Yemen.
nAdditionally, while UK passport holders are eligible to purchase a visa on arrival, it is generally advised that travellers to Algeria buy their visa in advance, in order to avoid complications.
Processing Time
The processing time for an Algerian visa often takes under a week, but this is not a universal rule.  An Algerian visa’s processing time depends very much on the type of visa, the nationality of the person applying, the time of year and other variables.  Therefore, it is advised that applicants start the application process well in advance of their scheduled trip.
Temporary Algerian Visas
Algerian Tourist Visa
An Algeria Tourist Visa is issued only to applicants entering the country for the purpose of tourism.  Applications for Algerian tourist visas require a number of items of documentation, in order for them to be approved.  The first is a certificate of accommodation (also known as a certificat d’hebergement legalisée) from the Algerian authorities.
Additionally, you will need to show evidence of your hotel / accommodation booking confirmation. Finally, in order for your Algerian visa to be approved, you will be required to have an invitation from a registered travel agency in Algeria. 
Please note:
Depending on where in Algeria you are travelling to, you may also be required to provide a travel itinerary.  This is usually required for travellers to the south of Algeria.
Algerian Transit Visa
Algeria also offers a transit visa.  Essentially this permits applicants to transfer through Algeria for while they are en route to another destination. Again, this visa class is strictly for travel purposes only, and holders cannot engage in any work or extend their stay while on this visa.
Algerian Business Visa
The application process for the Algerian business visa is very similar in process to the Algerian tourist visa.  However, applicants will also be required to show a letter of sponsorship from an acknowledged business as proof of their need to visit Algeria for business purposes.
The Algerian business visa grants holders the right to attend meetings, conferences and other business-related activities.  However, the holder is not permitted to be employed in any capacity during their time in Algeria.
Algerian Embassy Information
Consulate of Algeria

6 Hyde Park Gate
London
SW7 5EW
nTelephone: 020 7589 6885
Fax: 020  7589 7725
Website: www.algerianconsulate.org.uk
                                                                                                                                                                  Source: visabureau.com