UK market authorities said satellite communications provider EchoStar has less than a fortnight to make a formal bid to acquire Inmarsat, after it disclosed it owned a 3 per cent stake and significant bond holding in its target.

EchoStar made an initial approach for UK-based Inmarsat at the start of June for an undisclosed sum, a bid Reuters reported was rejected outright on grounds it significantly undervalued the company.

Under rules from the UK Takeover Panel, after expressing its initial interest EchoStar was required to disclose its position in Inmarsat and adhere to a deadline – given as 6 July – to make a formal acquisition approach.

In a filing, EchoStar said it held around 3 per cent of Inmarsat’s shares and 10 per cent of the company’s convertible bonds, which are due to mature and switch to equity in 2023.

Reuters estimated EchoStar’s stake in the company is worth around £82 million, with its bond holding valued at £51 million. Inmarsat’s market value is around £2.8 billion.

Inmarsat provides mobile satellite communications for a wide range of public and private sector organisations around the world. EchoStar is a US-headquarted company offering similar global services. Any deal would likely be subject to a lengthy regulatory approval process.