International Tax clarification UK.

Hi all , Need an advice for a freind who has migrated to UK . 

Got a notice for reconcillation of the tax amount for the assets/offshore/overseas. 

notice issued by the UK tax authorities - 
Information 
1 Staying there on PR . 
2 some savings account and fd in indian banks while working as NRI before migration . 
3Have not invested any amount from uk to india from earning in UK. 
4)No invetment assets/ofshore accounts.  basic salary and working there . 

In notice mentioned that amount are taxable under UK tax laws for the assets or investement . 

Any advice would be thankful for your help

Thanks in advance.