By Pablo Mayo Cerqueiro and Amy-Jo Crowley

LONDON British specialist lender Shawbrook made an offer for rival Co-op Bank and is weighing a fresh bid for embattled Metro Bank, people familiar with the matter told Reuters on Sunday.

Shawbrook, backed by private equity groups BC Partners and Pollen Street, tabled an indicative bid for Co-op in recent days, said the people, who spoke on condition of anonymity.

Separately, Shawbrook is considering a potential new bid for London-listed Metro Bank after several failed approaches earlier in the year, the sources said.

There is no certainty that a transaction will materialise, they cautioned.

Shawbrook, Pollen Street and Co-op Bank declined to comment. BC Partners and Metro Bank could not immediately be reached for comment.

Metro Bank has seen its shares tumble after news emerged that it had hired advisers to shore up its balance sheet after failing to gain key capital relief from banking regulators.

The bank has been exploring options to raise up to 600 million pounds ($734.28 million) of capital through equity and debt injections and asset sales.

Britain's Prudential Regulation Authority (PRA) is sounding out buyers over the weekend in hopes of finding a solution for ailing Metro Bank before markets open on Monday morning.

For Shawbrook, an acquisition of either Co-op or Metro Bank would give it greater scale as well as access to current deposit accounts, a cheaper source of funding for its loans than savings.

Reuters previously reported that Co-op Bank's owners had set an early October deadline for suitors.

($1 = 0.8171 pounds)

(Reporting by Pablo Mayo Cerqueiro and Amy-Jo Crowley; additional reporting by Iain Whithers; Editing by Ros Russell)