Troubled Johnston Press — owner of The Scotsman, the i newspaper and the Yorkshire Post — said on Tuesday it knew of “no operational or corporate reason” for a sudden and mysterious jump in its share price of more than 50%.

“As announced on 4 August 2016, the group continues to actively explore opportunities for the disposal of further assets,” said Johnston.

“These discussions continue to progress satisfactorily. Further announcements will be made as appropriate.”

 Johnston was due to meet an activist shareholder that is one of its top 10 shareholders on Tuesday.

Guernsey-based Crystal Amber Fund, which controls a 3.3% stake in Johnston, was expected to meet Johnston Press chairman Ian Russell.

Crystal Amber has a track record of activist campaigns that include putting pressure on firms to put themselves up for sale.

Johnston’s share price has collapsed over the past two years and its debt levels are causing concern among investors.

Last month, Moody’s Investors Service downgraded the bond (debt) ratings of Johnston Press deeper into “junk” territory, expressing concerns about the company’s liquidity.

Johnston Press publishes 13 paid-for daily newspapers, 154 paid-for weeklies, 37 free newspapers and a number of lifestyle magazines.