Interserve doubled the stake existing shareholders will retain in the British outsourcer to five percent on Wednesday as it set out details of a debt-for-equity deal with lenders aimed at averting a collapse like that of rival Carillion. 

Its banks have also agreed to provide an additional debt facility of 110 million pounds ($147 million), said Interserve, which reported its debt increased by almost 26 percent to 631 million pounds last year.

The company said it still faced challenges in several markets in construction and equipment services although its 2018 pretax loss of 111.3 million pounds was smaller than the 244.4 million shortfall it suffered a year earlier.

The company, which employs 68,000 people, maintains eight of Britain's 10 busiest railway stations and cleans thousands of London Underground carriages every evening.

Chief Executive Officer Debbie White is looking to cut costs and move away from low-margin contracts that have hurt the company.

"The business had too much complexity and a high level of organisational inefficiency... We've had to peel back the layers and make some changes to get to the underlying performance of the business," White told analysts on a call.

Chairman Glyn Barker admitted the company had entered some businesses it should not have done.

Interserve this month struck a rescue deal that would see lenders swap millions of pounds of debt for new shares. 

On Wednesday it said those new shares would be priced at 15.3 pence as it aims to raise 435 million pounds in a fully underwritten offering.

The deal, which will involve 19 new shares for every existing share, faces a vote by shareholders on March 15.

Interserve shares were down almost 18 percent at 17 pence at 1251 GMT.

Top shareholder Coltrane Asset Management this month called for eight company directors to be replaced but said it supported CEO White.

Coltrane could not be reached for immediate comment.

($1 = 0.7509 pounds)

(Reporting by Noor Zainab Hussain in Bengaluru; editing by Georgina Prodhan and Jason Neely) ((noor.hussain@thomsonreuters.com; Within UK +44 20 7542 1810; Outside UK +91 80 6749 2764; Reuters Messaging: noor.hussain.thomsonreuters.com@reuters.net))