Dubai — employer is asking me to pay for my own work permit. Is this legal?

I received a job offer from a company in Dubai (construction project manager role). The offer letter looks legitimate but they are asking me to pay AED 3,500 for the work permit processing and medical tests upfront before they can issue the employment contract. I've read that in the UAE the employer is supposed to cover work permit costs. Is this correct? The recruiter is saying this is standard practice for their company because they process hundreds of permits. I don't want to lose the opportunity but I also don't want to be scammed. Any advice?