Recruiters will often decline to get involved with a jobseeker unless they already have the right to work in the UK. That's their prerogative - They don't want to be held liable for any immigration issues.
You will need to sort a visa directly with an employer. First, an employer has to be a registered Tier 2 sponsor in order to be able to hire you and offer you visa sponsorship. If the job you're looking for isn't in national shortage, then they need to put the job through the resident labour market test before they can offer you sponsorship. This means they need to post it online for a month on two separate listings with NO other qualified applicants. You can see that this would be a big problem for most people seeking work. Ultimately it means that an employer has to show that they were unable to find anyone with the right to work who was qualified for the job. There's also a required minimum salary which needs to be offered.
Question is, are you qualified in any shortage area? If not, then you are just wasting your time, as there is a large pool of eligible workers - including EU until Brexit is complete, and you will be at the back of the queue.
I have used reed site extensively and always I end up with a recruiting consultant telling me that I am not eligible as I do not have a work permit..
I think I should see the job, trace the person in employment company and reach him?
any other idea?
Yes, I am in Oil and Energy field owrking as engineer
If you don't have permission to work in the UK, there's no way you'll get a job from overseas. Even if you do have a work permit, it can be difficult to get a job in the UK.
Unless you have a specialised skill that not many people in the UK possess, then there's no incentive for a UK based employer to consider you over any other non-EU applicant who is already in the UK and looking for work, just because you want to get a job in the UK.
Many jobs posted online are actually posted through recruitment agencies (when the company name isn't listed), but as you know recruiters won't get involved with someone who doesn't have the right to work in the UK. You would have to apply directly to an employer who is a Tier 2 visa sponsor. Mechanical and electrical engineers in the oil/gas industry are in national shortage, so you probably need to make this clear on your CV or cover letter if you're applying to a qualifying job. Even so, as WCCG says, unless they're in desperate need to fill the position they're still going to find someone in the UK who can do the job.
Using a recruiter is a waste of time. Maybe look at energy companies and see if they have a "careers" section on their website where you can apply directly. Make sure they're Tier 2 sponsors.