When an Arab teacher applies to your institution to teach English, you should give them a chance. Why? Because they might just be what you are looking for.
If you have any have any doubts, give them a chance to earn the benefit of the doubt. Your company profile probably boasts of equal opportunities; put your company profile into action. This does not mean that you should hire teachers who lack proficiency of the English language; just make sure before you delete the e-mail with their curriculum vitae after checking their nationality.
Once you shortlist candidates after going through the resumes you have, you are now going to conduct an interview. The interview will tell you a lot about a person and you can also check their proficiency in a language, and check if their accent is clear or not. Thus, if you are worried about the Arab teachers, you will have a fair assessment once the interview is carried out.
English is becoming an international language, some say it is already an international language. So many schools and universities around the world teach in English. Thus, students from Arab countries that have attended schools and universities where they have been taught in English will most likely have native or native-like proficiency in English. Even if a person has never been to an English speaking country or has never studied there, does not mean that they cannot be proficient in English with a clear accent. The world is becoming smaller by the day. Students are exposed to native accents through television, internet, and even their well-traveled teachers. English is an international language which should be taught by qualified teachers worldwide.
An international language should not only be taught by those who were born and raised in a native-English speaking country. Or those who applied later on for a citizenship to one of these countries. A native-speaker cannot be judged on the basis of a passport they carry. A native-speaker should be judged on their proficiency.
You may have been working in the HR or in a recruitment office for a long time. And you may have disregarded all the Arab teachers who have applied for positions to teach English. Think again, are you sure they would not be suitable for the job? If you are not sure, conduct an interview; let them earn the benefit of your doubt.