A rescue package for troubled construction giant Carillion has been rejected, putting Scottish projects at risk.

The developer tabled a business restructure plan on Wednesday but it is understood it failed to convince its lenders it was a strong enough proposition.

Despite its being commissioned for a range of significant government and infrastructure contracts, Carillion is struggling under a £900m mountain of debt and a £590m pension deficit.

Among its current projects are the extension of platforms at Edinburgh Waverley station, a new £745m Aberdeen bypass and two facilities management contracts with the Ministry of Defence (MoD) worth £158m which cover 83 military sites in Scotland.

The Wolverhampton-based firm's precarious finances are the focus of a meeting between the UK Government, pension authorities and stakeholders on Friday, which will attempt to negotiate a package to help it avoid collapse.

Sky News has reported Carillion has put one of the UK's largest accountancy firms on standby in the event talks fail and the company falls into administration.

Trade unions have urged ministers to step in to protect the 19,500 jobs across Britain that are now at risk.

Talks between the firm and lenders HSBC, Barclays, Santander and Royal Bank of Scotland have centred on options to reduce debts and recapitalise or restructure the group's balance sheet.

Carillion is a major supplier to the UK Government and key contractor in the first phase of building the £56bn HS2 rail line.

Its share price plunge more than 70% in the past six months after a shock profit warning wiped almost £600m from the company's stock market value in July last year.