Before starting i would suggest you to consult with some legal experts,
Coming to your case there are two conditions 1. Your current employment 2. New employment opportunity.
1. If you are not declaring your experience then you are not entitled to take any benefit of it.
2. If you are working in any public sector you have to complete certain probation period and there is some agreement and guarantee which you have to pay or full fill the term and condition if you are running away fro it it will be considered as breech of contract and you might be under legal scanner.Therefore it is advisable to inform your current employer and follow the legal exit formalities.
3. If you are not disclosing your previous employment to existing company again you are under big legal problem because industry is not aware of your previous conduct and while filling the joining forms you have to declare your previous cases in registered on you in any court or legal bodies.